CVE-2026-55040
Weak Authentication in Microsoft SharePoint. CISA confirmed attackers exploit it and added it to its Known Exploited Vulnerabilities catalog on 18 August 2026.
- Product
- Microsoft SharePoint
- Added to CISA's catalog
- Federal fix-by date
- Ransomware
- No known use in ransomware campaigns
- Vendor advisories
- Sources
- CISA’s catalog, NVD entry
CISA’s description.
Microsoft SharePoint contains a weak authentication vulnerability which allows an unauthorized attacker to bypass a security feature over a network.
More from Microsoft this year.
- CVE-2026-96951 Command Injection, added
- CVE-2026-65660 Code Injection, added
- CVE-2026-85880 Heap-Based Buffer Overflow, added
- CVE-2026-81963 Link Following, added
- CVE-2019-1068 Remote Code Execution, added
- CVE-2026-33824 Double Free, added
- CVE-2026-68820 Use-After-Free, added
- CVE-2026-50522 Deserialization of Untrusted Data, added
Every flaw CISA confirmed exploited in the last 30 days is on the exploit watch. This is not security advice. Check the vendor’s advisory before acting. From CISA’s catalog of 4 November 2026.