Evidence used
- CISA confirms exploitation in the wild.
- Exploitation requires an existing local or physical foothold with privileges.
- EPSS is 0.39% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-81963High confidence
Microsoft Windows Link Following Vulnerability
Microsoft · Windows
7.8HighCVSS 3.1
Patch now
Patch availableCISA confirms exploitation in the wild and lists 2026-09-22 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 8 Sep 2026
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict local access and enforce least privilege on affected hosts.
- Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
- Confirm that the asset runs Microsoft Windows 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.
CISA confirms exploitation in the wild and lists 2026-09-22 as the remediation due date.
Patch available01
What, why and how
Microsoft Windows Update Stack contains a link following vulnerability that allows a local attacker to escalate privileges locally up to SYSTEM.
What
Microsoft Windows Update Stack contains a link following vulnerability that allows a local attacker to escalate privileges locally up to SYSTEM.
Why
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
How
An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
Microsoft Windows Update Stack contains a link following vulnerability that allows a local attacker to escalate privileges locally up to SYSTEM.
Why
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
How
An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
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 2026-09-08.
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
- local access → Improper Link Resolution Before File Access ('Link Following') → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Local
- 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-59 ↗
CWE-59: Improper Link Resolution Before File Access ('Link Following'). The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:CCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.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
- The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
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
- Windows 11 Version 24H2: 10.0.26100.0 < 10.0.26100.9445
- Windows 11 Version 23H2: 10.0.22631.0 < 10.0.22631.7582
- Windows Server 2025: 10.0.26100.0 < 10.0.26100.33438
- Windows 11 version 26H1: 10.0.28000.0 < 10.0.28000.2954
- Windows Server 2025 (Server Core installation): 10.0.26100.0 < 10.0.26100.33438
- Windows 11 Version 25H2: 10.0.26200.0 < 10.0.26200.9445
- Action
- Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
Official vendor articles4 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.
- September 8, 2026—KB5122880 (OS Build 22631.7582) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 24 Oct 2026September 8, 2026—KB5122880 (OS Build 22631.7582) Applies To Windows 11 version 23H2, all editions This cumulative update for Windows 11, version 23H2 (KB5122880), includes the latest security fixes and improvements, along with non-security updates from last month’s optional preview release. Visit the Windows release
- September 8, 2026—KB5122871 (OS Build 26100.33438) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 23 Oct 2026September 8, 2026—KB5122871 (OS Build 26100.33438) Applies To Windows Server 2025, all editions This cumulative update for Windows Server 2025 (KB5122871), includes the latest security fixes and improvements, along with non-security updates from last month’s optional preview release. Visit the Windows release health d
- September 8, 2026—KB5124008 (OS Builds 26200.9445 and 26100.9445) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 22 Oct 2026September 8, 2026—KB5124008 (OS Builds 26200.9445 and 26100.9445) Applies To Windows 11 version 25H2, all editions Windows 11 version 24H2, all editions Want a quick overview?: Watch the Windows 11 release note video for this update. Announcements and messages This section provides key notifications related to this r
- September 8, 2026-KB5124012 (OS Build 28000.2954) | Microsoft Support →Original publisher ↗Searchable text snapshot · Captured 22 Oct 2026September 8, 2026—KB5124012 (OS Build 28000.2954) Applies To Windows 11 version 26H1, all editions This cumulative update for Windows 11, version 26H1 (KB5124012) includes the latest security fixes and improvements, along with non-security updates from last month's optional preview release. Visit the Windows release h
04
Evidence and provenance
Published 8 Sept 2026 · Last source change 14 Oct 2026, 23:14 UTC · CWE-59 · Improper Link Resolution Before File Access ('Link Following')
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-09-09
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-73889
Product sourceCISA KEV
Remediation sourceCVE/CNA references
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.CNA ↗
- Before
- 10.0.22631.0 < 10.0.22631.7582; 10.0.26100.0 < 10.0.26100.9445; 10.0.26200.0 < 10.0.26200.9445; 10.0.28000.0 < 10.0.28000.2954; 10.0.26100.0 < 10.0.26100.33438 · 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
- Windows 11 version 23H2: 10.0.22631.0 < 10.0.22631.7582; Windows 11 Version 23H2: 10.0.22631.0 < 10.0.22631.7582; Windows 11 Version 24H2: 10.0.26100.0 < 10.0.26100.9445; Windows 11 Version 25H2: 10.0.26200.0 < 10.0.26200.9445; Windows 11 version 26H1: 10.0.28000.0 < 10.0.28000.2954; Windows Server 2025: 10.0.26100.0 < 10.0.26100.33438; Windows Server 2025 (Server Core installation): 10.0.26100.0 < 10.0.26100.33438 · 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-2026-73889)
- ENISA EUVD mappingEUVD-2026-73889 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-73889"}
- BlackTree coverageBlackTree article coverage changed from no BlackTree article to 2 BlackTree articles.BlackTree editorial ↗
- Before
- no BlackTree article
- After
- 2 BlackTree articles
- Vendor guidanceAuthoritative vendor guidance changed: added patch: msrc.microsoft.com/CVE-2026-81963; added remediation: msrc.microsoft.com/CVE-2026-81963.secure@microsoft.com ↗
- Before
- no authoritative guidance recorded
- After
- patch: msrc.microsoft.com/CVE-2026-81963 · remediation: msrc.microsoft.com/CVE-2026-81963
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- 10.0.22631.0 < 10.0.22631.7582; 10.0.26100.0 < 10.0.26100.9445; 10.0.26200.0 < 10.0.26200.9445; 10.0.28000.0 < 10.0.28000.2954; 10.0.26100.0 < 10.0.26100.33438 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- 10.0.22631.0 < 10.0.22631.7582; 10.0.26100.0 < 10.0.26100.9445; 10.0.26200.0 < 10.0.26200.9445; 10.0.28000.0 < 10.0.28000.2954; 10.0.26100.0 < 10.0.26100.33438 · 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.
- Remediation statusRemediation status changed from Awaiting fix to Patch available.secure@microsoft.com ↗
- Before
- Awaiting fix
- After
- Patch available
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
CVE published
Added to CISA KEV
Fixed release or patch reference recorded
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.