DaystoPatch

MicrosoftExploited incident

Microsoft Windows Ancillary Function Driver for WinSock Heap-Based Buffer Overflow Vulnerability

CVE-2025-21418High, CVSS 7.8In CISA's Known Exploited Vulnerabilities catalog since 11 Feb 2025

  • Exploited before a fix

Automated timeline. Not yet checked by a researcher, so it doesn't count toward any grade.

FixedFixed for every supported version on the day it became public.

Response

Silence
same day
First public report to first vendor statementUnverified source
Exposure
same day
First public report to first fix
Follow-through
same day
First public report to a fix for every supported version
  • Vendor silent
  • Vendor statement, no fix
  • Fixed for some versions
  • Fixed when disclosed
  • Date only, no time of day

Timeline and evidence

Open a moment to see its source and archived quote.

  1. First public report

    CVE.org record CVE-2025-21418ClaimedQuote verified

    Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

    CVE record published.

    Recorded time
    Precision
    To the minute
    Origin
    Claimed. The date the source gives.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:8275d3ebae7cf1c7…
    Used in metrics
    Yes
    Dispute this timestamp
    3 more sources for this moment
    Microsoft advisory CVE-2025-21418ClaimedQuote not found in archive11 Feb 2025

    Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability. [Publicly Disclosed:No;Exploited:Yes;Latest Software Release:Exploitation Detected]

    The vendor's own disclosure.

    Source
    Microsoft advisory CVE-2025-21418 vendor advisory
    Recorded time
    Precision
    Date only (no time of day is shown)
    Origin
    Claimed. The date the source gives.
    Quote check
    Not found in the archived copy. Treat with caution.
    Snapshot
    sha256:b849f79e34a5d967…
    Used in metrics
    No, kept for the record
    Dispute this timestamp
    CISA KEV (CVE-2025-21418)ClaimedQuote verified11 Feb 2025

    Microsoft Windows Ancillary Function Driver for WinSock Heap-Based Buffer Overflow Vulnerability

    Added to CISA's KEV catalog on 2025-02-11.

    Recorded time
    Precision
    Date only (no time of day is shown)
    Origin
    Claimed. The date the source gives.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:ef8fffede5c47200…
    Used in metrics
    No, kept for the record
    Dispute this timestamp
    Bluesky postClaimedQuote not checked yet11 Feb 2025, 18:18 UTC

    ID: CVE-2025-21418

    Earliest third-party post we hold.

    Source
    Bluesky post social
    Recorded time
    Precision
    To the minute
    Origin
    Claimed. The date the source gives.
    Quote check
    Not checked yet
    Snapshot
    No archived snapshot
    Used in metrics
    No, kept for the record
    Dispute this timestamp

  2. Vendor statement

    date onlysame dayUnverified: quote not found in the archived copy

    Microsoft advisory CVE-2025-21418ClaimedQuote not found in archive

    Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability. [Publicly Disclosed:No;Exploited:Yes;Latest Software Release:Exploitation Detected]

    Source
    Microsoft advisory CVE-2025-21418 vendor advisory
    Recorded time
    Precision
    Date only (no time of day is shown)
    Origin
    Claimed. The date the source gives.
    Quote check
    Not found in the archived copy. Treat with caution.
    Snapshot
    sha256:b849f79e34a5d967…
    Used in metrics
    Yes
    Dispute this timestamp

  3. First workaround

    No official mitigation found yet.

  4. First fix

    date onlysame day

    Microsoft advisory CVE-2025-21418ClaimedQuote verified

    Information published.

    Vendor Fix listed at the first revision

    Source
    Microsoft advisory CVE-2025-21418 vendor advisory
    Recorded time
    Precision
    Date only (no time of day is shown)
    Origin
    Claimed. The date the source gives.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:89da748553d2f469…
    Used in metrics
    Yes
    Dispute this timestamp

  5. Fixed for all versions

    date onlysame day

    Microsoft advisory CVE-2025-21418ClaimedQuote verified

    Information published.

    every Known Affected product has a Vendor Fix and no later revision announces more updates

    Source
    Microsoft advisory CVE-2025-21418 vendor advisory
    Recorded time
    Precision
    Date only (no time of day is shown)
    Origin
    Claimed. The date the source gives.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:89da748553d2f469…
    Used in metrics
    Yes
    Dispute this timestamp

Send this to your boss

No brief for this incident yet. We write one for every open incident and every critical bug exploited before a fix.

Affected products

  • Windows
  • Windows 10 Version 1607 for 32-bit Systems
  • Windows 10 Version 1607 for x64-based Systems
  • Windows 10 Version 1809 for 32-bit Systems
  • Windows 10 Version 1809 for x64-based Systems
  • Windows 10 Version 21H2 for 32-bit Systems
  • Windows 10 Version 21H2 for ARM64-based Systems
  • Windows 10 Version 21H2 for x64-based Systems
  • Windows 10 Version 22H2 for 32-bit Systems
  • Windows 10 Version 22H2 for ARM64-based Systems
  • Windows 10 Version 22H2 for x64-based Systems
  • Windows 10 for 32-bit Systems
  • Windows 10 for x64-based Systems
  • Windows 11 Version 22H2 for ARM64-based Systems
  • Windows 11 Version 22H2 for x64-based Systems
  • Windows 11 Version 23H2 for ARM64-based Systems
  • Windows 11 Version 23H2 for x64-based Systems
  • Windows 11 Version 24H2 for ARM64-based Systems
  • Windows 11 Version 24H2 for x64-based Systems
  • Windows Server 2008 R2 for x64-based Systems Service Pack 1
  • Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
  • Windows Server 2008 for 32-bit Systems Service Pack 2
  • Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
  • Windows Server 2008 for x64-based Systems Service Pack 2
  • Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
  • Windows Server 2012
  • Windows Server 2012 (Server Core installation)
  • Windows Server 2012 R2
  • Windows Server 2012 R2 (Server Core installation)
  • Windows Server 2016
  • Windows Server 2016 (Server Core installation)
  • Windows Server 2019
  • Windows Server 2019 (Server Core installation)
  • Windows Server 2022
  • Windows Server 2022 (Server Core installation)
  • Windows Server 2022, 23H2 Edition (Server Core installation)
  • Windows Server 2025
  • Windows Server 2025 (Server Core installation)

Related

Microsoft report card