Microsoft SharePoint Weak Authentication Vulnerability
CVE-2026-55040 Exploited
Microsoft SharePoint contains a weak authentication vulnerability which allows an unauthorized attacker to bypass a security feature over a network.
Being exploited in the wild
Catalogued 18 August 2026 · US federal remediation deadline 21 August 2026
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for…
Exploit code is also public: Public PoC · Nuclei template
- NucleiMicrosoft SharePoint Server - JWT Authentication Bypass
- Public PoCsfewer-r7/CVE-2026-5504059 stars
- Public PoCl0ggg/CVE-2026-550403 stars
- Public PoCzenzue/CVE-2026-55040
- Public PoCmaxprog-svg/CVE-2026-55040-Mass-Exploit
- Public PoCvirologi-info/mssharepoint-scanner
Assessment
- CVSS
- Not yet scored
- Severity
- Unscored
- Known exploited
- Yes — listed in the CISA KEV catalog
- Exploit availability
- CISA KEV, Public PoC, Nuclei template
- Published
- 18 August 2026
- Last updated
- 18 August 2026
- Affected
- Microsoft · SharePoint
- Weakness
- CWE-1390
At the source
References
Query this programmatically
Agents can read this through the MCP endpoint, or over HTTP:
curl https://www.cve.zerocrew.in/api/cve/CVE-2026-55040