DaystoPatch

MicrosoftExploited incident

Microsoft Windows Shell Protection Mechanism Failure Vulnerability

CVE-2026-21510High, CVSS 8.8In CISA's Known Exploited Vulnerabilities catalog since 10 Feb 2026

  • 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-2026-21510ClaimedQuote verified

    Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network.

    CVE record published.

    Recorded time
    Precision
    To the minute
    Origin
    Claimed. The date the source gives.
    Quote check
    Found in the archived copy
    Snapshot
    sha256:951df3707dbf3458…
    Used in metrics
    Yes
    Dispute this timestamp
    5 more sources for this moment
    Microsoft advisory CVE-2026-21510ClaimedQuote not found in archive10 Feb 2026

    Windows Shell Security Feature Bypass Vulnerability. Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network. [Publicly

    The vendor's own disclosure.

    Source
    Microsoft advisory CVE-2026-21510 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:d9bb066b76e90c8c…
    Used in metrics
    No, kept for the record
    Dispute this timestamp
    CISA KEV (CVE-2026-21510)ClaimedQuote verified10 Feb 2026

    Microsoft Windows Shell Protection Mechanism Failure Vulnerability

    Added to CISA's KEV catalog on 2026-02-10.

    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 yet10 Feb 2026, 19:12 UTC

    Microsoft’s February 2026 Patch Tuesday Addresses 54 CVEs (CVE-2026-21510, CVE-2026-21513) 2 Critical 51 Important 1 Moderate 0 Low Microsoft addresses 54 CVEs in the February 2026 Patch Tuesday ...

    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
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    No archived snapshot
    Used in metrics
    No, kept for the record
    Dispute this timestamp
    Hacker NewsClaimedQuote not checked yet15 Mar 2026, 00:55 UTC

    CVE-2010-2568, CVE-2015-0096, CVE-2017-8464, CVE-2026-21510... OLE/COM mess from the early '90s and internal assumption that only Microsoft code ever touches the serialised data or calls certain object methods provided some

    Earliest third-party post we hold.

    Source
    Hacker News hn
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    To the minute
    Origin
    Claimed. The date the source gives.
    Quote check
    Not checked yet
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    No archived snapshot
    Used in metrics
    No, kept for the record
    Dispute this timestamp
    Mastodon postClaimedQuote not checked yet27 Apr 2026, 20:20 UTC

    A Shortcut to Coercion: Incomplete Patch of APT28's Zero-Day Leads to CVE-2026-32202 # CVE_2026_32202 # APT28 # CVE_2026_21510 https://www. akamai.com/blog/security-resea

    Earliest third-party post we hold.

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

  2. Vendor statement

    date onlysame dayUnverified: quote not found in the archived copy

    Microsoft advisory CVE-2026-21510ClaimedQuote not found in archive

    Windows Shell Security Feature Bypass Vulnerability. Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network. [Publicly

    Source
    Microsoft advisory CVE-2026-21510 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:d9bb066b76e90c8c…
    Used in metrics
    Yes
    Dispute this timestamp

  3. First workaround

    No official mitigation found yet.

  4. First fix

    date onlysame day

    Microsoft advisory CVE-2026-21510ClaimedQuote verified

    Information published.

    Vendor Fix listed at the first revision

    Source
    Microsoft advisory CVE-2026-21510 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
    sha256:145f3a76364b0038…
    Used in metrics
    Yes
    Dispute this timestamp

  5. Fixed for all versions

    date onlysame day

    Microsoft advisory CVE-2026-21510ClaimedQuote verified

    Information published.

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

    Source
    Microsoft advisory CVE-2026-21510 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
    sha256:145f3a76364b0038…
    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 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 11 Version 25H2 for ARM64-based Systems
  • Windows 11 Version 25H2 for x64-based Systems
  • Windows 11 Version 26H1 for ARM64-based Systems
  • Windows 11 version 26H1 for x64-based Systems
  • 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