CVE-2025-21418
Actively exploited. CVE-2025-21418 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-02-11) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.
Microsoft Windows Ancillary Function Driver for WinSock contains a heap-based buffer overflow vulnerability that allows for privilege escalation, enabling a local attacker to gain SYSTEM privileges.
CSIRTS triage
- What
- A heap-based buffer overflow vulnerability in the Windows Ancillary Function Driver for WinSock allows for privilege escalation.
- Who is affected
- Local attackers on systems running the affected Windows version.
- Urgency
- Immediate action is required due to active exploitation and critical severity.
- Action
- Install the latest security updates for Microsoft Windows.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 72% of all EPSS-scored CVEs.
Advisory coverage (1)
- criticalexploitedCVE-2025-21418: Microsoft Windows Ancillary Function Driver for WinSock Heap-Based Buffer Overflow Vulnerabili…cisa-kev · 2025-02-11
External references
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