Patch tracker / CVE reference / CVE-2026-20959

CVE-2026-20959

Critical severity Microsoft vulnerability, CVSS 9.8. Fixed by 3 Microsoft security updates.

Critical

Risk summary

CVSS base
9.8
EPSS exploit probability
31%
Severity
Critical

Exploitation and severity

Not in the CISA KEV catalog. EPSS exploit probability 31%. CVSS 9.8 (Critical).

This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.

What to do

Elevated priority: high severity or a meaningful exploitation probability, sooner if an affected product is internet-facing. In Intune or Defender, confirm whether the fixing updates KB5002822, KB5002825, KB5002828 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.

Official patch for CVE-2026-20959

Apply the Microsoft security updates below to fix CVE-2026-20959. Each KB page links to the Microsoft Update Catalog download for every affected product.

KB5002822KB5002825KB5002828

Affected products

  • Microsoft Office 2016 (32-bit edition)
  • Microsoft Office 2016 (64-bit edition)
  • Microsoft SharePoint Server 2019

Authoritative references

NVD detailMicrosoft MSRCFIRST.org EPSS

Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.

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Lexicon: the terms on this page
CVE
Common Vulnerabilities and Exposures. A unique ID for one publicly known vulnerability, such as CVE-2025-1234.
KB
Microsoft Knowledge Base article. The identifier for a specific Microsoft update.
KEV
CISA Known Exploited Vulnerabilities. CVEs confirmed exploited in the wild. Fix these first.
CVSS
Common Vulnerability Scoring System. A standardized Severity score from 0 to 10.
EPSS
Exploit Prediction Scoring System. The probability a CVE will be exploited in the next 30 days.
MSRC
Microsoft Security Response Center. Microsoft's Patch Tuesday advisories and KB-to-CVE mapping.
NVD
National Vulnerability Database (NIST). Authoritative CVE metadata and CVSS scores.
Ransomware
The vulnerability is linked to known ransomware activity.