DaystoPatch

MicrosoftExploited incident

Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability

CVE-2026-45659High, CVSS 8.8In CISA's Known Exploited Vulnerabilities catalog since 1 Jul 2026

  • Known ransomware use

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 fixUnverified source
Follow-through
same day
First public report to a fix for every supported versionUnverified source
  • 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

    date onlyUnverified: quote not found in the archived copy

    Microsoft advisory CVE-2026-45659ClaimedQuote not found in archive

    Microsoft SharePoint Remote Code Execution Vulnerability. Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network. [Publicly

    The vendor's own disclosure.

    Source
    Microsoft advisory CVE-2026-45659 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
    sha256:6bdb850cbdf1c060…
    Used in metrics
    Yes
    Dispute this timestamp
    4 more sources for this moment
    Bluesky postClaimedQuote not checked yet22 May 2026, 13:10 UTC

    🔗 CVE : CVE-2026-45659, CVE-2026-45659

    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
    CVE.org record CVE-2026-45659ClaimedQuote verified22 May 2026, 22:04 UTC

    Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code 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
    sha256:3d639be7e829d276…
    Used in metrics
    No, kept for the record
    Dispute this timestamp
    Mastodon postClaimedQuote not checked yet26 May 2026, 12:20 UTC

    execute malicious code remotely - and it's crucial you update your servers ASAP to stay safe. The vulnerability, tracked as CVE-2026-45659, has a CVSS score of 8.8, making it a prime target for attackers. https:// osintsights.com/microsoft-fixe s-sharepoint-flaw-that-exposes-servers-to-remote-code

    Earliest third-party post we hold.

    Source
    Mastodon 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
    CISA KEV (CVE-2026-45659)ClaimedQuote verified1 Jul 2026

    Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability

    Added to CISA's KEV catalog on 2026-07-01.

    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

  2. Vendor statement

    date onlysame dayUnverified: quote not found in the archived copy

    Microsoft advisory CVE-2026-45659ClaimedQuote not found in archive

    Microsoft SharePoint Remote Code Execution Vulnerability. Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network. [Publicly

    Source
    Microsoft advisory CVE-2026-45659 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
    sha256:6bdb850cbdf1c060…
    Used in metrics
    Yes
    Dispute this timestamp

  3. First workaround

    No official mitigation found yet.

  4. First fix

    date onlysame day

    Microsoft advisory CVE-2026-45659ClaimedQuote verified

    Information published.

    Vendor Fix listed at the first revision

    Source
    Microsoft advisory CVE-2026-45659 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:c8e475f7b6a3cbff…
    Used in metrics
    Yes
    Dispute this timestamp

  5. Fixed for all versions

    date onlysame day

    Microsoft advisory CVE-2026-45659ClaimedQuote verified

    Information published.

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

    Source
    Microsoft advisory CVE-2026-45659 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:c8e475f7b6a3cbff…
    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

  • SharePoint Server
  • Microsoft SharePoint Enterprise Server 2016
  • Microsoft SharePoint Server 2019
  • Microsoft SharePoint Server Subscription Edition

Related

Microsoft report card