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CVE-2026-20963

CRITICALCVSS 9.8/10Actively ExploitedEPSS 31.11%

Last modified

CVE-2026-20963 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.. CISA has confirmed active exploitation in the wild. EPSS estimates a 31.11% chance of exploitation in the next 30 days.

Description

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

Metrics

CVSS 3.1
9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
31.11%

98.0th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by .

Weakness Enumeration

Affected Software

VendorProductVersions
MicrosoftSharepoint Server< 16.0.19127.20442
MicrosoftSharepoint Server2016
MicrosoftSharepoint Server2019

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-20963?
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
How severe is CVE-2026-20963?
CVE-2026-20963 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 31.11% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.
How do I fix CVE-2026-20963?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-20963?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST