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CVE-2026-77899 Microsoft CVE debrief

CVE-2026-77899 is a high-severity vulnerability in Windows Security Center that allows an authorized attacker to elevate privileges locally. The CVE record was published on 2026-09-08T18:20:40.133Z and has not been modified since then. The NVD entry is currently Analyzed. This vulnerability is a use-after-free issue, indicating a high severity with a CVSS score of 7. Defenders responsible for Windows Security Center systems, especially those with high-risk exposure, should prioritize patching this vulnerability. The vulnerability allows for local privilege escalation, emphasizing the need for prompt patch application and verification.

Vendor
Microsoft
Product
Windows 11 Version 24H2
CVSS
HIGH 7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-08
Original CVE updated
2026-09-16
Advisory published
2026-09-08
Advisory updated
2026-09-16

Who should care

Defenders responsible for Windows Security Center systems, especially those with high-risk exposure, should prioritize patching this vulnerability.

Why it matters

CVE-2026-77899 is a high-severity vulnerability in Windows Security Center that allows an authorized attacker to elevate privileges locally. Defenders should prioritize patching, especially for high-risk systems, and verify patch application to prevent local privilege escalation.

  • Verify patch application to prevent local privilege escalation.
  • Monitor system logs for potential exploitation attempts.
  • Assess system exposure and prioritize patching for high-risk systems.

Technical summary

The vulnerability is a use-after-free issue in Windows Security Center that allows an authorized attacker to elevate privileges locally. The CVSS score is 7, indicating a high severity. This vulnerability has a significant impact on systems with high-risk exposure, emphasizing the need for defenders to prioritize patching and verify patch application. The vulnerability allows for local privilege escalation.

Defensive priority

Defenders should prioritize patching this vulnerability, especially for systems with high-risk exposure. Verify and apply the available patch from Microsoft.

Recommended defensive actions

  • Apply the available patch from Microsoft.
  • Verify system exposure and prioritize patching for high-risk systems.
  • Monitor system logs for potential exploitation attempts.

Evidence notes

The vulnerability is described as a use-after-free issue in Windows Security Center. Microsoft has provided a patch for this vulnerability. The CVE record was published on 2026-09-08T18:20:40.133Z and has not been modified since then. The NVD entry is currently Analyzed. Evidence is limited to CVE Program and NVD sources. Defenders should verify patch application to prevent local privilege escalation and monitor system logs for potential exploitation attempts.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-77899 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-77899

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-77899 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-77899

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.