Evidence used
- CISA confirms exploitation in the wild.
- EPSS is 2.10% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-65660High confidence
Microsoft SharePoint Code Injection Vulnerability
Microsoft · SharePoint
8.8HighCVSS 3.1
Patch now
Patch availableCISA confirms exploitation in the wild and lists 2026-09-28 as the remediation due date.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:Critical, raised one band.upgradedsince 25 Sep 2026
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
- Confirm that the asset runs Microsoft SharePoint and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
msrc_CVE-2026-65660 · CSAF 2.0 · revision 3 · finalMicrosoft Security Response CenterMicrosoft SharePoint Server Remote Code Execution Vulnerability
The vendor explicitly identifies these products as affected by this CVE.
- Microsoft SharePoint Server Subscription Edition <16.0.19725.20522
- Microsoft SharePoint Server 2019 <16.0.10417.20198
- Microsoft SharePoint Enterprise Server 2016 <16.0.5565.1001
- Summary
- Microsoft
- Remediation
- 16.0.5565.1001:Security Update:https://support.microsoft.com/help/5002905
CISA confirms exploitation in the wild and lists 2026-09-28 as the remediation due date.
Patch available01
What, why and how
Microsoft SharePoint contains a code injection vulnerability which could allow an authorized attacker to execute code over a network.
What
Microsoft SharePoint contains a code injection vulnerability which could allow an authorized attacker to execute code over a network.
Why
Untrusted data can cross into a code-evaluation path and be interpreted as executable instructions.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may execute code or commands in the affected security context.
What
Microsoft SharePoint contains a code injection vulnerability which could allow an authorized attacker to execute code over a network.
Why
Untrusted data can cross into a code-evaluation path and be interpreted as executable instructions.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may execute code or commands in the affected security context.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation Confirmed in the wild
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2026-09-25.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Improper Control of Generation of Code ('Code Injection') → execute code or commands in the affected security context
- Attack surface
- Network
- Privileges required
- Low: a basic authenticated account is required
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-94 ↗
CWE-94: Improper Control of Generation of Code ('Code Injection'). The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:CCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- Fixed
- Action
- 16.0.5565.1001:Security Update:https://support.microsoft.com/help/5002905
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
Official vendor articles5 stored documents
Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.
- Description of the security update for SharePoint Server 2016: August 11, 2026 (KB5002905) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 24 Oct 2026Description of the security update for SharePoint Server 2016: August 11, 2026 (KB5002905) Applies To SharePoint Server 2016 Summary Important If you're currently running SharePoint Workflow Manager, you must install the SharePoint Workflow Manager (KB5002799) to your farm before you install this cumulative update.
- Description of the security update for SharePoint Server 2016 Language Pack: August 11, 2026 (KB5002906) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 24 Oct 2026Description of the security update for SharePoint Server 2016 Language Pack: August 11, 2026 (KB5002906) Applies To SharePoint Server 2016 Summary Important If you're running Microsoft SharePoint Server 2013-type workflows, you must install the August 2025 update for SharePoint Workflow Manager to your farm before you
- Description of the security update for SharePoint Server Subscription Edition: August 11, 2026 (KB5002893) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 23 Oct 2026Description of the security update for SharePoint Server Subscription Edition: August 11, 2026 (KB5002893) Applies To SharePoint Server Subscription Edition Summary Important If you're currently running SharePoint Workflow Manager, you must install SharePoint Workflow Manager (KB5002799) to your farm before you instal
- Description of the security update for SharePoint Server 2019: August 11, 2026 (KB5002894) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 23 Oct 2026Description of the security update for SharePoint Server 2019: August 11, 2026 (KB5002894) Applies To SharePoint Server 2019 Summary Important If you're currently running SharePoint Workflow Manager, you must install the SharePoint Workflow Manager (KB5002799) to your farm before you install this cumulative update.
- Description of the security update for SharePoint Server 2019 Language Pack: August 11, 2026 (KB5002896) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 23 Oct 2026Description of the security update for SharePoint Server 2019 Language Pack: August 11, 2026 (KB5002896) Applies To SharePoint Server 2019 Summary Important If you're running Microsoft SharePoint Server 2013-type workflows, you must install the August 2025 update for SharePoint Workflow Manager to your farm before you
04
Evidence and provenance
Published 11 Aug 2026 · Last source change 21 Oct 2026, 20:52 UTC · CWE-94 · Improper Control of Generation of Code ('Code Injection')
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-56431
Product sourceVendor CSAF · Microsoft Security Response Center
Remediation sourceVendor CSAF · Microsoft Security Response Center
CWE sourceOther authority
NVD statusNVD enriched
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.CISA KEV ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: 16.0.5565.1001:Security Update:https://support.microsoft.com/help/5002905
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- Affected versionsThe structured affected or fixed version information changed.CISA KEV ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: 16.0.5565.1001:Security Update:https://support.microsoft.com/help/5002905
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- Affected versionsThe structured affected or fixed version information changed.CISA KEV ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: 16.0.5565.1001:Security Update:https://support.microsoft.com/help/5002905
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- Affected versionsThe structured affected or fixed version information changed.CISA KEV ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: 16.0.5565.1001:Security Update:https://support.microsoft.com/help/5002905
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- Vendor guidanceAuthoritative vendor guidance changed: added remediation: msrc.microsoft.com/CVE-2026-65660; removed remediation: cyber.gc.ca/al26-023-vulnerability-impacting-microsoft-sharepoint-server-cve-2026-65660.secure@microsoft.com ↗
- Before
- patch: msrc.microsoft.com/CVE-2026-65660 · remediation: cyber.gc.ca/al26-023-vulnerability-impacting-microsoft-sharepoint-server-cve-2026-65660
- After
- patch: msrc.microsoft.com/CVE-2026-65660 · remediation: msrc.microsoft.com/CVE-2026-65660
- Affected versionsThe structured affected or fixed version information changed.CISA KEV ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: The Cyber Centre recommends that organizations upgrade affected Microsoft SharePoint instances to a fixed version: Affected products Affected versions Fixed Versions Microsoft SharePoint Enterprise Server 2016 All versions prior to 16.0.5565.1001 Version 16.0.5565.1001 Microsoft SharePoint Server 2019 All Versions prior to 16.0.10417.20198 Version 16.0.10417.20198 Microsoft SharePoint Server Subscription Edition All versions prior to 16.0.19725.20522 Version 16.0.19725.20522 Important note: Microsoft SharePoint Enterprise Server 2016 Footnote 6 and Server 2019 Footnote 7 are end of life as of July 15, 2026 . Organizations are urged to migrate to a supported version. The Cyber Centre also recommends organizations to: Identify all on-premises SharePoint Server instances, particularly those exposed to the Internet, and ensure they are running supported versions of Microsoft SharePoint Server. Apply the latest Microsoft security updates to all affected SharePoint Server deployments, including SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016. Reduce the attack surface by restricting or eliminating direct internet exposure of SharePoint servers where possible, limiting access to SharePoint Central Administration and other management interfaces. Strengthen access controls by reviewing SharePoint environments for unnecessary or inactive accounts, removing unused accounts, and enforcing multi-factor authentication (MFA) for administrators and other privileged users. Harden SharePoint deployments by enabling Antimalware Scan Interface (AMSI) integration for SharePoint web applications and configuring AMSI Request Body Scan Mode to Full Mode where operationally feasible. Monitor for indicators of compromise and exploitation activity, including: unusual administrative activity or suspicious authenticated access attempts unexpected web part modifications or unauthorized configuration changes unauthorized authentication attempts and privilege escalation activity suspicious access to IIS machine keys evidence of deserialization attacks, web shell deployment, or malicious process execution unusual requests targeting SharePoint services Microsoft Defender or AMSI detections related to SharePoint exploitation activity Conduct ongoing log and security monitoring of SharePoint, IIS, endpoint security, and authentication logs to detect and investigate suspicious activity. In addition, the Cyber Centre strongly recommends that organizations review and implement the Cyber Centre’s Top 10 IT Security Actions with an emphasis on the following topics Footnote 8 : patch operating systems and applications harden operating systems and applications isolate web-facing applications Should activity matching the content of this alert be discovered, recipients are encouraged to report via My Cyber Portal , or email contact@cyber.gc.ca .
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- ENISA known-exploited stateENISA EUVD now records this CVE in its known-exploited dataset.ENISA EUVD ↗
- Before
- not listed in ENISA EUVD known-exploited dataset
- After
- listed in ENISA EUVD known-exploited dataset (EUVD-2026-56431)
- Vendor guidanceAuthoritative vendor guidance changed: added remediation: msrc.microsoft.com/CVE-2026-65660; removed remediation: cyber.gc.ca/al26-023-vulnerability-impacting-microsoft-sharepoint-server-cve-2026-65660.secure@microsoft.com ↗
- Before
- patch: msrc.microsoft.com/CVE-2026-65660 · remediation: cyber.gc.ca/al26-023-vulnerability-impacting-microsoft-sharepoint-server-cve-2026-65660
- After
- patch: msrc.microsoft.com/CVE-2026-65660 · remediation: msrc.microsoft.com/CVE-2026-65660
- Affected versionsThe structured affected or fixed version information changed.CISA KEV ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: The Cyber Centre recommends that organizations upgrade affected Microsoft SharePoint instances to a fixed version: Affected products Affected versions Fixed Versions Microsoft SharePoint Enterprise Server 2016 All versions prior to 16.0.5565.1001 Version 16.0.5565.1001 Microsoft SharePoint Server 2019 All Versions prior to 16.0.10417.20198 Version 16.0.10417.20198 Microsoft SharePoint Server Subscription Edition All versions prior to 16.0.19725.20522 Version 16.0.19725.20522 Important note: Microsoft SharePoint Enterprise Server 2016 Footnote 6 and Server 2019 Footnote 7 are end of life as of July 15, 2026 . Organizations are urged to migrate to a supported version. The Cyber Centre also recommends organizations to: Identify all on-premises SharePoint Server instances, particularly those exposed to the Internet, and ensure they are running supported versions of Microsoft SharePoint Server. Apply the latest Microsoft security updates to all affected SharePoint Server deployments, including SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016. Reduce the attack surface by restricting or eliminating direct internet exposure of SharePoint servers where possible, limiting access to SharePoint Central Administration and other management interfaces. Strengthen access controls by reviewing SharePoint environments for unnecessary or inactive accounts, removing unused accounts, and enforcing multi-factor authentication (MFA) for administrators and other privileged users. Harden SharePoint deployments by enabling Antimalware Scan Interface (AMSI) integration for SharePoint web applications and configuring AMSI Request Body Scan Mode to Full Mode where operationally feasible. Monitor for indicators of compromise and exploitation activity, including: unusual administrative activity or suspicious authenticated access attempts unexpected web part modifications or unauthorized configuration changes unauthorized authentication attempts and privilege escalation activity suspicious access to IIS machine keys evidence of deserialization attacks, web shell deployment, or malicious process execution unusual requests targeting SharePoint services Microsoft Defender or AMSI detections related to SharePoint exploitation activity Conduct ongoing log and security monitoring of SharePoint, IIS, endpoint security, and authentication logs to detect and investigate suspicious activity. In addition, the Cyber Centre strongly recommends that organizations review and implement the Cyber Centre’s Top 10 IT Security Actions with an emphasis on the following topics Footnote 8 : patch operating systems and applications harden operating systems and applications isolate web-facing applications Should activity matching the content of this alert be discovered, recipients are encouraged to report via My Cyber Portal , or email contact@cyber.gc.ca .
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- Vendor guidanceAuthoritative vendor guidance changed: added remediation: msrc.microsoft.com/CVE-2026-65660; removed remediation: cyber.gc.ca/al26-023-vulnerability-impacting-microsoft-sharepoint-server-cve-2026-65660.secure@microsoft.com ↗
- Before
- patch: msrc.microsoft.com/CVE-2026-65660 · remediation: cyber.gc.ca/al26-023-vulnerability-impacting-microsoft-sharepoint-server-cve-2026-65660
- After
- patch: msrc.microsoft.com/CVE-2026-65660 · remediation: msrc.microsoft.com/CVE-2026-65660
- Affected versionsThe structured affected or fixed version information changed.CISA KEV ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: The Cyber Centre recommends that organizations upgrade affected Microsoft SharePoint instances to a fixed version: Affected products Affected versions Fixed Versions Microsoft SharePoint Enterprise Server 2016 All versions prior to 16.0.5565.1001 Version 16.0.5565.1001 Microsoft SharePoint Server 2019 All Versions prior to 16.0.10417.20198 Version 16.0.10417.20198 Microsoft SharePoint Server Subscription Edition All versions prior to 16.0.19725.20522 Version 16.0.19725.20522 Important note: Microsoft SharePoint Enterprise Server 2016 Footnote 6 and Server 2019 Footnote 7 are end of life as of July 15, 2026 . Organizations are urged to migrate to a supported version. The Cyber Centre also recommends organizations to: Identify all on-premises SharePoint Server instances, particularly those exposed to the Internet, and ensure they are running supported versions of Microsoft SharePoint Server. Apply the latest Microsoft security updates to all affected SharePoint Server deployments, including SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016. Reduce the attack surface by restricting or eliminating direct internet exposure of SharePoint servers where possible, limiting access to SharePoint Central Administration and other management interfaces. Strengthen access controls by reviewing SharePoint environments for unnecessary or inactive accounts, removing unused accounts, and enforcing multi-factor authentication (MFA) for administrators and other privileged users. Harden SharePoint deployments by enabling Antimalware Scan Interface (AMSI) integration for SharePoint web applications and configuring AMSI Request Body Scan Mode to Full Mode where operationally feasible. Monitor for indicators of compromise and exploitation activity, including: unusual administrative activity or suspicious authenticated access attempts unexpected web part modifications or unauthorized configuration changes unauthorized authentication attempts and privilege escalation activity suspicious access to IIS machine keys evidence of deserialization attacks, web shell deployment, or malicious process execution unusual requests targeting SharePoint services Microsoft Defender or AMSI detections related to SharePoint exploitation activity Conduct ongoing log and security monitoring of SharePoint, IIS, endpoint security, and authentication logs to detect and investigate suspicious activity. In addition, the Cyber Centre strongly recommends that organizations review and implement the Cyber Centre’s Top 10 IT Security Actions with an emphasis on the following topics Footnote 8 : patch operating systems and applications harden operating systems and applications isolate web-facing applications Should activity matching the content of this alert be discovered, recipients are encouraged to report via My Cyber Portal , or email contact@cyber.gc.ca .
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- Affected versionsThe structured affected or fixed version information changed.Microsoft Security Response Center ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: 16.0.5565.1001:Security Update:https://support.microsoft.com/help/5002905
- Affected versionsThe structured affected or fixed version information changed.CISA KEV ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: The Cyber Centre recommends that organizations upgrade affected Microsoft SharePoint instances to a fixed version: Affected products Affected versions Fixed Versions Microsoft SharePoint Enterprise Server 2016 All versions prior to 16.0.5565.1001 Version 16.0.5565.1001 Microsoft SharePoint Server 2019 All Versions prior to 16.0.10417.20198 Version 16.0.10417.20198 Microsoft SharePoint Server Subscription Edition All versions prior to 16.0.19725.20522 Version 16.0.19725.20522 Important note: Microsoft SharePoint Enterprise Server 2016 Footnote 6 and Server 2019 Footnote 7 are end of life as of July 15, 2026 . Organizations are urged to migrate to a supported version. The Cyber Centre also recommends organizations to: Identify all on-premises SharePoint Server instances, particularly those exposed to the Internet, and ensure they are running supported versions of Microsoft SharePoint Server. Apply the latest Microsoft security updates to all affected SharePoint Server deployments, including SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016. Reduce the attack surface by restricting or eliminating direct internet exposure of SharePoint servers where possible, limiting access to SharePoint Central Administration and other management interfaces. Strengthen access controls by reviewing SharePoint environments for unnecessary or inactive accounts, removing unused accounts, and enforcing multi-factor authentication (MFA) for administrators and other privileged users. Harden SharePoint deployments by enabling Antimalware Scan Interface (AMSI) integration for SharePoint web applications and configuring AMSI Request Body Scan Mode to Full Mode where operationally feasible. Monitor for indicators of compromise and exploitation activity, including: unusual administrative activity or suspicious authenticated access attempts unexpected web part modifications or unauthorized configuration changes unauthorized authentication attempts and privilege escalation activity suspicious access to IIS machine keys evidence of deserialization attacks, web shell deployment, or malicious process execution unusual requests targeting SharePoint services Microsoft Defender or AMSI detections related to SharePoint exploitation activity Conduct ongoing log and security monitoring of SharePoint, IIS, endpoint security, and authentication logs to detect and investigate suspicious activity. In addition, the Cyber Centre strongly recommends that organizations review and implement the Cyber Centre’s Top 10 IT Security Actions with an emphasis on the following topics Footnote 8 : patch operating systems and applications harden operating systems and applications isolate web-facing applications Should activity matching the content of this alert be discovered, recipients are encouraged to report via My Cyber Portal , or email contact@cyber.gc.ca .
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- CISA KEV stateCISA KEV now confirms exploitation in the wild.CISA KEV ↗
- Before
- not listed in CISA KEV
- After
- listed in CISA KEV since 2026-09-25
- Vendor guidanceAuthoritative vendor guidance changed: added remediation: msrc.microsoft.com/CVE-2026-65660; removed remediation: cyber.gc.ca/al26-023-vulnerability-impacting-microsoft-sharepoint-server-cve-2026-65660.secure@microsoft.com ↗
- Before
- patch: msrc.microsoft.com/CVE-2026-65660 · remediation: cyber.gc.ca/al26-023-vulnerability-impacting-microsoft-sharepoint-server-cve-2026-65660
- After
- patch: msrc.microsoft.com/CVE-2026-65660 · remediation: msrc.microsoft.com/CVE-2026-65660
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: The Cyber Centre recommends that organizations upgrade affected Microsoft SharePoint instances to a fixed version: Affected products Affected versions Fixed Versions Microsoft SharePoint Enterprise Server 2016 All versions prior to 16.0.5565.1001 Version 16.0.5565.1001 Microsoft SharePoint Server 2019 All Versions prior to 16.0.10417.20198 Version 16.0.10417.20198 Microsoft SharePoint Server Subscription Edition All versions prior to 16.0.19725.20522 Version 16.0.19725.20522 Important note: Microsoft SharePoint Enterprise Server 2016 Footnote 6 and Server 2019 Footnote 7 are end of life as of July 15, 2026 . Organizations are urged to migrate to a supported version. The Cyber Centre also recommends organizations to: Identify all on-premises SharePoint Server instances, particularly those exposed to the Internet, and ensure they are running supported versions of Microsoft SharePoint Server. Apply the latest Microsoft security updates to all affected SharePoint Server deployments, including SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016. Reduce the attack surface by restricting or eliminating direct internet exposure of SharePoint servers where possible, limiting access to SharePoint Central Administration and other management interfaces. Strengthen access controls by reviewing SharePoint environments for unnecessary or inactive accounts, removing unused accounts, and enforcing multi-factor authentication (MFA) for administrators and other privileged users. Harden SharePoint deployments by enabling Antimalware Scan Interface (AMSI) integration for SharePoint web applications and configuring AMSI Request Body Scan Mode to Full Mode where operationally feasible. Monitor for indicators of compromise and exploitation activity, including: unusual administrative activity or suspicious authenticated access attempts unexpected web part modifications or unauthorized configuration changes unauthorized authentication attempts and privilege escalation activity suspicious access to IIS machine keys evidence of deserialization attacks, web shell deployment, or malicious process execution unusual requests targeting SharePoint services Microsoft Defender or AMSI detections related to SharePoint exploitation activity Conduct ongoing log and security monitoring of SharePoint, IIS, endpoint security, and authentication logs to detect and investigate suspicious activity. In addition, the Cyber Centre strongly recommends that organizations review and implement the Cyber Centre’s Top 10 IT Security Actions with an emphasis on the following topics Footnote 8 : patch operating systems and applications harden operating systems and applications isolate web-facing applications Should activity matching the content of this alert be discovered, recipients are encouraged to report via My Cyber Portal , or email contact@cyber.gc.ca .
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- Affected versionsThe structured affected or fixed version information changed.Canadian Centre for Cyber Security ↗
- Before
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: The Cyber Centre recommends that organizations upgrade affected Microsoft SharePoint instances to a fixed version: Affected products Affected versions Fixed Versions Microsoft SharePoint Enterprise Server 2016 All versions prior to 16.0.5565.1001 Version 16.0.5565.1001 Microsoft SharePoint Server 2019 All Versions prior to 16.0.10417.20198 Version 16.0.10417.20198 Microsoft SharePoint Server Subscription Edition All versions prior to 16.0.19725.20522 Version 16.0.19725.20522 Important note: Microsoft SharePoint Enterprise Server 2016 Footnote 6 and Server 2019 Footnote 7 are end of life as of July 15, 2026 . Organizations are urged to migrate to a supported version. The Cyber Centre also recommends organizations to: Identify all on-premises SharePoint Server instances, particularly those exposed to the Internet, and ensure they are running supported versions of Microsoft SharePoint Server. Apply the latest Microsoft security updates to all affected SharePoint Server deployments, including SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Server 2016. Reduce the attack surface by restricting or eliminating direct internet exposure of SharePoint servers where possible, limiting access to SharePoint Central Administration and other management interfaces. Strengthen access controls by reviewing SharePoint environments for unnecessary or inactive accounts, removing unused accounts, and enforcing multi-factor authentication (MFA) for administrators and other privileged users. Harden SharePoint deployments by enabling Antimalware Scan Interface (AMSI) integration for SharePoint web applications and configuring AMSI Request Body Scan Mode to Full Mode where operationally feasible. Monitor for indicators of compromise and exploitation activity, including: unusual administrative activity or suspicious authenticated access attempts unexpected web part modifications or unauthorized configuration changes unauthorized authentication attempts and privilege escalation activity suspicious access to IIS machine keys evidence of deserialization attacks, web shell deployment, or malicious process execution unusual requests targeting SharePoint services Microsoft Defender or AMSI detections related to SharePoint exploitation activity Conduct ongoing log and security monitoring of SharePoint, IIS, endpoint security, and authentication logs to detect and investigate suspicious activity. In addition, the Cyber Centre strongly recommends that organizations review and implement the Cyber Centre’s Top 10 IT Security Actions with an emphasis on the following topics Footnote 8 : patch operating systems and applications harden operating systems and applications isolate web-facing applications Should activity matching the content of this alert be discovered, recipients are encouraged to report via My Cyber Portal , or email contact@cyber.gc.ca .
- BlackTree coverageBlackTree article coverage changed from no BlackTree article to 1 BlackTree article.BlackTree editorial ↗
- Before
- no BlackTree article
- After
- 1 BlackTree article
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- 16.0.0 < 16.0.5565.1001; 16.0.0 < 16.0.10417.20198; 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- After
- Microsoft SharePoint Enterprise Server 2016: 16.0.0 < 16.0.5565.1001; Microsoft SharePoint Server 2019: 16.0.0 < 16.0.10417.20198; Microsoft SharePoint Server Subscription Edition: 16.0.0 < 16.0.19725.20522 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- SeveritySeverity changed from Medium to High.CNA ↗
- Before
- Medium
- After
- High
- CVSS scoreCVSS score changed from 6.5 (CVSS 3.1 · CNA · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C) to 8.8 (CVSS 3.1 · CNA · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C).CNA ↗
- Before
- 6.5 (CVSS 3.1 · CNA · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C)
- After
- 8.8 (CVSS 3.1 · CNA · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C)
CVE published
Added to CISA KEV
Fixed release or patch reference recorded
Fixed release recorded from official guidance
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.