PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-83738 Microsoft CVE debrief

A use-after-free vulnerability exists in the Windows Ancillary Function Driver for WinSock, which allows an authorized attacker to elevate privileges locally. Multiple Windows versions and platforms are affected, including Windows 10 (1607, 1809, 21H2, 22H2), Windows 11 (23H2, 24H2, 25H2, 26H1, 26H2), and various Windows Server editions (2012, 2012 R2, 2016, 2019, 2022, 2025). This vulnerability can lead to full system compromise if exploited. Defenders should prioritize patching affected systems to prevent exploitation. The CVE Program and NVD provide official records of this vulnerability, and Microsoft has released a patch for this issue. The vulnerability allows for local and

Vendor
Microsoft
Product
Windows 10 Version 1607
CVSS
HIGH 7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-13
Original CVE updated
2026-10-13
Advisory published
2026-10-13
Advisory updated
2026-10-13

Who should care

Defenders responsible for Windows systems, especially those with high-risk exposure or multiple vulnerabilities, should prioritize patching. This includes administrators of Windows 10, Windows 11, and Windows Server environments.

Why it matters

CVE-2026-83738 is a high-severity vulnerability in Windows Ancillary Function Driver for WinSock, allowing local privilege escalation. Defenders should prioritize patching affected systems to prevent exploitation.

  • Local privilege escalation can lead to full system compromise.
  • Attackers can use this vulnerability to gain elevated access.
  • Patching is crucial to prevent exploitation.
  • Verify affected versions and apply patches immediately.

Technical summary

The vulnerability exists in the Windows Ancillary Function Driver for WinSock due to a use-after-free condition. An authorized attacker can exploit this to elevate privileges locally. Affected versions include Windows 10 (1607, 1809, 21H2, 22H2), Windows 11 (23H2, 24H2, 25H2, 26H1, 26H2), and various Windows Server editions (2012, 2012 R2, 2016, 2019, 2022, 2025).

Defensive priority

Defenders should prioritize patching this vulnerability, as it allows for local privilege escalation. Systems with multiple vulnerabilities or exposed services may be at higher risk.

Recommended defensive actions

  • Apply patches from Microsoft for the affected Windows versions.
  • Conduct a thorough inventory of affected systems and prioritize patching based on risk and exposure.
  • Monitor systems for indicators of compromise related to this vulnerability.

Evidence notes

The CVE Program and NVD provide official records of this vulnerability. Microsoft has released a patch for this issue. The vulnerability exists in the Windows Ancillary Function Driver for WinSock due to a use-after-free condition. An authorized attacker can exploit this to elevate privileges locally. Affected versions include Windows 10 (1607, 1809, 21H2, 22H2), Windows 11 (23H2, 24H2, 25H2, 26H1, 26H2), and various Windows Server editions (2012, 2012 R2, 2016, 2019, 2022, 2025). Def

Sources and references

Verified primary and authoritative sources

  • CVE-2026-83738 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-83738

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

  • CVE-2026-83738 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-83738

    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.