Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.47% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-66807High confidence
Microsoft Office Graphics Component Remote Code Execution Vulnerability
Microsoft · Microsoft 365 Apps for Enterprise
7.8HighCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productHigh technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 2 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict local access and enforce least privilege on affected hosts.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Microsoft Microsoft 365 Apps for Enterprise 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.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 2 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 2 affected or under-investigation product states without a fixed product state in the same current advisory
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.
CVE-2026-66807 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityconsole: dangerouslySetInnerHTML with unescaped subscription identifiers in SharedResourceWarning
The vendor explicitly identifies these products as affected by this CVE.
- multicluster-engine/console-mce-rhel9 as a component of Multicluster Engine for Kubernetes
- rhacm2/console-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2
- Summary
- A flaw was found in console. The `getCodeSpan` helper in `SharedResourceWarning.js` constructs an HTML string using string concatenation without proper HTML encoding. This unescaped string is then rendered via React's `dangerouslySetInnerHTML`. While current Kubernetes DNS-1123 name validation prevents immediate exploitation, any future relaxation of this validation or an alternative data source could enable stored Cross-Site Scripting (XSS) in the hub console. This could allow an attacker to inject malicious scripts into web pages viewed by other users.
- Remediation
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 2 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
Stack-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
What
Stack-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
Why
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
How
An attacker operating through local access may attempt exploitation without authentication after a user interaction. If successful, the issue may execute code or commands in the affected security context.
What
Stack-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
Why
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
How
An attacker operating through local access may attempt exploitation without authentication after a user interaction. 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 No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
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 → Stack-based Buffer Overflow → execute code or commands in the affected security context
- Attack surface
- Local
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- Required interaction required
- 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-121 ↗
CWE-121: Stack-based Buffer Overflow. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
- 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:N/UI:R/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.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.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. - Fix availability varies by product
- Affected
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
04
Evidence and provenance
Published 11 Aug 2026 · Last source change 29 Sept 2026, 20:22 UTC · CWE-121 · Stack-based Buffer Overflow
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-2026-56749
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
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
- Vendor guidanceAuthoritative vendor guidance changed: removed remediation: acn.gov.it/aggiornamenti-mensili-microsoft-23.secure@microsoft.com ↗
- Before
- remediation: acn.gov.it/aggiornamenti-mensili-microsoft-23 · vendor advisory: msrc.microsoft.com/CVE-2026-66807
- After
- vendor advisory: msrc.microsoft.com/CVE-2026-66807
- Remediation statusRemediation status changed from Mitigation available to Awaiting fix.secure@microsoft.com ↗
- Before
- Mitigation available
- After
- Awaiting fix
- Vendor guidanceAuthoritative vendor guidance changed: removed remediation: acn.gov.it/aggiornamenti-mensili-microsoft-23.secure@microsoft.com ↗
- Before
- remediation: acn.gov.it/aggiornamenti-mensili-microsoft-23 · vendor advisory: msrc.microsoft.com/CVE-2026-66807
- After
- vendor advisory: msrc.microsoft.com/CVE-2026-66807
- Remediation statusRemediation status changed from Mitigation available to Awaiting fix.secure@microsoft.com ↗
- Before
- Mitigation available
- After
- Awaiting fix
- Vendor guidanceAuthoritative vendor guidance changed: removed remediation: acn.gov.it/aggiornamenti-mensili-microsoft-23.secure@microsoft.com ↗
- Before
- remediation: acn.gov.it/aggiornamenti-mensili-microsoft-23 · vendor advisory: msrc.microsoft.com/CVE-2026-66807
- After
- vendor advisory: msrc.microsoft.com/CVE-2026-66807
- Remediation statusRemediation status changed from Mitigation available to Awaiting fix.secure@microsoft.com ↗
- Before
- Mitigation available
- After
- Awaiting fix
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- 16.0.1 < https://aka.ms/OfficeSecurityReleases; 19.0.0 < https://aka.ms/OfficeSecurityReleases; 1.0.0 < 16.112.26081010; 16.0.0 < https://aka.ms/OfficeSecurityReleases; 16.0.1 < 16.112.26081010; 16.0.0 < 16.112.26081010 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- Microsoft 365 Apps for Enterprise: 16.0.1 < https://aka.ms/OfficeSecurityReleases; Microsoft Office 2019: 19.0.0 < https://aka.ms/OfficeSecurityReleases; Microsoft Office 365 for Mac: 1.0.0 < 16.112.26081010; Microsoft Office LTSC 2021: 16.0.1 < https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC 2024: 16.0.0 < https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC for Mac 2021: 16.0.1 < 16.112.26081010; Microsoft Office LTSC for Mac 2024: 16.0.0 < 16.112.26081010 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: msrc.microsoft.com/CVE-2026-66807.secure@microsoft.com ↗
- Before
- no authoritative guidance recorded
- After
- vendor advisory: msrc.microsoft.com/CVE-2026-66807
- Remediation statusRemediation status changed from Awaiting fix to Mitigation available.CSIRT Italia ↗
- Before
- Awaiting fix
- After
- Mitigation available
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.