CVE-2026-85900: Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code

Q: How do I fix CVE-2026-85900?

sharepoint server: upgrade to 16.0.20326.20190. Exact commands for each OS are on this page.

Q: Is CVE-2026-85900 being exploited?

CVE-2026-85900 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-85900 affect?

CVE-2026-85900 affects sharepoint server. Severity is high (CVSS 8.8). Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

Q: How urgent is CVE-2026-85900?

Priority 54/100. High severity; On your watchlist

This month

HIGH 8.8WATCHLISTUPGRADE

CVE-2026-85900 is a high-severity flaw (CVSS 8.8) affecting sharepoint server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.5% (top 26%)
CISA exploited list	No
Weakness	CWE-502
Published	2026-10-13
Last modified	2026-10-14

Publisher (CNA): Microsoft Corporation · Vendor: microsoft

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-10-13 19:21 UTCPublished CVE record published
2026-10-14 19:44 UTCUpdated Record last modified

microsoft sharepoint server UPGRADE

Affected: < 16.0.20326.20190

Fixed in: 16.0.20326.20190

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy sharepoint-server || rpm -q sharepoint-server || sharepoint-server --version

2. UPGRADE to 16.0.20326.20190 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade sharepoint-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade sharepoint-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

Fedora ELN · edk2 · FIXED · 20260812-12.eln159 · FEDORA-2026-e316b6370a · source

sudo dnf upgrade --advisory=FEDORA-2026-e316b6370a

Fedora 46 · perl-Mojo-DOM58 · FIXED · 3.003-1.fc46 · FEDORA-2026-d5412af3de · source

sudo dnf upgrade --advisory=FEDORA-2026-d5412af3de

Microsoft SharePoint Server Subscription Edition · KB5002927 · FIXED · 16.0.20326.20190 · KB5002927 · source

Install KB5002927 via Windows Update, then verify: Get-HotFix -Id KB5002927

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-85900?

sharepoint server: upgrade to 16.0.20326.20190. Exact commands for each OS are on this page.

Is CVE-2026-85900 being exploited?

CVE-2026-85900 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-85900 affect?

CVE-2026-85900 affects sharepoint server. Severity is high (CVSS 8.8). Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

How urgent is CVE-2026-85900?

Priority 54/100. High severity; On your watchlist

Software pages

SharePoint vulnerabilities · Microsoft Office vulnerabilities

Related CVEs

CVE-2026-65660 HIGH 8.8 EXPLOITED UPGRADE Microsoft SharePoint Code Injection Vulnerability
CVE-2026-70321 HIGH 8.8 UPGRADE Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code
CVE-2026-70326 HIGH 8.8 UPGRADE Server-side request forgery (ssrf) in Microsoft Office SharePoint allows an authorized attacker to elevate pri
CVE-2026-57105 HIGH 8.0 UPGRADE Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office Share
CVE-2026-97783 HIGH 8.1 DOWNGRADE Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office Share

References

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