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Report · Reddit CybersecurityAbout CVE-2026-45659Published

Microsoft SharePoint Has a New RCE Flaw. If You Haven’t Patched Yet, Go Do That.

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Authoritative record:CVE-2026-45659· High 8.8

Exploited in the wild · KEV due 4 Jul 2026 : upgrade to 16.0.5552.1002 now.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
KEV deadline
 US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates
Patch
Available – fixed in 16.0.5552.1002, 16.0.10417.20128, 16.0.19725.20280
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

  1. Disclosed: evidence found.

    CVE published 22 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: evidence found.

    Listed in CISA KEV 40 days after disclosure

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

Timeline

  1. CVE ID reserved

    by Microsoft Corporation

    , 10 days before disclosure

  2. CVE published

    on cve.org

    , t = 0

  3. In Threat Radar

    record ingested

    , 25 minutes after disclosure

  4. Added to CISA KEV (opens in a new tab)

    exploitation confirmed · ransomware use known

    , 40 days after disclosure

  5. KEV remediation due

    US federal deadline

    , 43 days after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade Microsoft SharePoint to 16.0.5552.1002 (Enterprise Server 2016) or 16.0.10417.20128 (Server 2019) or 16.0.19725.20280 (Server Subscription Edition).

Affected software

ProductAffectedFixed in
MicrosoftMicrosoft SharePoint Enterprise Server 2016Affected
  • >=16.0.0 <16.0.5552.1002
Fixed in
  • 16.0.5552.1002
MicrosoftMicrosoft SharePoint Server 2019Affected
  • >=16.0.0 <16.0.10417.20128
Fixed in
  • 16.0.10417.20128
MicrosoftMicrosoft SharePoint Server Subscription EditionAffected
  • >=16.0.0 <16.0.19725.20280
Fixed in
  • 16.0.19725.20280

AI-suggested

Microsoft has released official security updates for SharePoint Server Subscription Edition, SharePoint Server 2019, and SharePoint Enterprise Server 2016 to address CVE-2026-45659. Organizations should apply these patches immediately to mitigate the risk. No additional mitigation steps are indicated by the vendor advisory. Patch status is confirmed as official-fix.

Discussion

A critical remote code execution (RCE) vulnerability, tracked as CVE-2026-45659, affects Microsoft SharePoint Server versions including Subscription Edition, 2019, and Enterprise Server 2016. The flaw arises from deserialization of untrusted data, allowing an authenticated attacker with low privileges (Site Member) to execute code remotely over the network. Microsoft has released security updates to address this vulnerability. Although Microsoft assesses exploitation likelihood as low, the vulnerability's nature and SharePoint's history of being targeted warrant prompt patching. No known exploits are currently reported in the wild.

References

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