{"id":"CVE-2025-21418","published":"2025-02-11T18:15:40Z","modified":"2026-06-17T08:43:19Z","title":"Microsoft Windows Ancillary Function Driver for WinSock Heap-Based Buffer Overflow Vulnerability","vendor":"Microsoft","product":"Windows","tier":"core","eol":null,"description":{"text":"Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability","provenance":"source","from":"NVD"},"summary":{"text":"The flaw is a heap-based buffer overflow in the Windows Ancillary Function Driver for WinSock (afd.sys), a component of Microsoft Windows that handles socket-related operations. The vulnerability is an elevation of privilege issue within that driver. An attacker with local access and low-privileged credentials, requiring no user interaction, could exploit the overflow to gain elevated privileges on the affected system.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:14:38Z"},"cvss":{"score":7.8,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.02132,"percentile":0.8193,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2025-02-11","dueDate":"2025-03-04","ransomware":false,"requiredAction":"Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.","notes":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21418 ; https://nvd.nist.gov/vuln/detail/CVE-2025-21418","provenance":"source"},"vulncheckKev":{"dateAdded":"2025-02-11","exploitedFirstSeen":"2025-02-11","ransomware":false,"evidence":[{"url":"https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2025-Feb","date":"2025-02-11"},{"url":"https://docs.google.com/spreadsheets/d/1lkNJ0uQwbeC1ZTRrxdtuPLCIl7mlUreoKfSIgajnSyY/edit","date":"2025-02-11"},{"url":"https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2025-21418","date":"2025-02-11"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2025-02-11"},{"url":"https://www.loginsoft.com/reports/annually/vulnerability-intelligence-report-2025","date":"2026-01-20"}],"evidenceTotal":5,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 30, 2026","url":"https://otx.alienvault.com/pulse/6ae35d889ea92b4ce19c2680","created":"2026-10-29"},{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"}],"provenance":"machine"},"cwes":[{"id":"CWE-122","name":"Heap-based Buffer Overflow"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21418","tags":["Patch","Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21418","tags":["US Government Resource"]}],"techniques":[{"id":"T1068","name":"Exploitation for Privilege Escalation","tactics":["privilege-escalation"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Buffer Overflow","mappingType":"exploitation_technique","evidence":[],"comment":"Exploiting this buffer overflow vulnerability could lead to an adversary gaining elevated privileges on the machine, leading to the potential for process injection using malicious code, as well as data loss.","confidence":"high"},{"id":"T1005","name":"Data from Local System","tactics":["collection"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Buffer Overflow","mappingType":"primary_impact","evidence":[],"comment":"Exploiting this buffer overflow vulnerability could lead to an adversary gaining elevated privileges on the machine, leading to the potential for process injection using malicious code, as well as data loss.","confidence":"high"},{"id":"T1055","name":"Process Injection","tactics":["privilege-escalation","stealth"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Buffer Overflow","mappingType":"primary_impact","evidence":[],"comment":"Exploiting this buffer overflow vulnerability could lead to an adversary gaining elevated privileges on the machine, leading to the potential for process injection using malicious code, as well as data loss.","confidence":"high"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2025-2476","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2025-2476","exploited":true,"exploitedSince":"2025-02-11","provenance":"source"},"exploits":[],"exploitSources":null,"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1068"],"provenance":"source"},{"stage":"primary","techniques":["T1055","T1005"],"provenance":"source"}],"timeline":[{"date":"2025-02-11","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21418","provenance":"source"},{"date":"2025-02-11","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2025-Feb","provenance":"source"},{"date":"2025-02-11","kind":"kev","label":"Added to CISA KEV","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2025-02-11","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2025-2476","provenance":"source"}],"speed":{"daysToPublicExploit":null,"firstExploitFrom":null,"daysToKev":0},"priority":{"score":59.8,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV listing","points":0.0,"detail":"added 626 days ago"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":16.39,"detail":"percentile 0.8193"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":0.0,"detail":"none found"},{"name":"Mentioned in OTX pulses","points":3.0,"detail":"50 pulses"},{"name":"CVSS severity","points":5.46,"detail":"base score 7.8"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]},"lineage":{"familyId":"fam-class-microsoft-windows-cwe-122"}}