Microsoft SharePoint Server
CVE-2026-56164: Microsoft SharePoint Server Missing Authentication for Critical Function Vulnerability
What it is
Microsoft SharePoint contains a missing authentication for critical function vulnerability that allows an unauthorized attacker to elevate privileges over a network.
What to do
Schedule the vendor fix into this week’s change window, prioritising internet-facing and business-critical systems. Confirm the fix is applied everywhere, not just where it was easy.
- Priority
- This week: Schedule into this week’s change window.
- Severity (CVSS)
- 5.3 medium
- CISA assessment (SSVC)
- actively exploited; attackers can automate it at scale; partial control or data exposure
- Exploit probability (EPSS, 30 days)
- 1.0%, higher than 62% of all CVEs
- Added to CISA KEV
- 14 July 2026
- CISA fix-by date
- 17 July 2026 (US federal agencies; a sensible deadline for everyone)
- Ransomware use
- Not known
- Weakness
- CWE-306
References
- NIST NVD entry
- CISA KEV entry
- msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56164
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56164
Sources: CISA Known Exploited Vulnerabilities · FIRST Exploit Prediction Scoring System (EPSS) · NIST National Vulnerability Database · CISA Vulnrichment (SSVC), via the CVE Program. This product uses data from the NVD API but is not endorsed or certified by the NVD. Summaries are machine-written from CISA’s description; treat the vendor’s advisory as the authority for fixes.