CVE-2026-55040
critical · 9.1Actively exploitedOn the CISA Known Exploited Vulnerabilities catalog
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 evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
A public exploit / detection template exists
Weaponised detection is publicly available, which meaningfully raises real-world risk regardless of CVSS. nuclei-templates →
Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weaknesses
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| microsoft | sharepoint_server | < 16.0.19725.20434 |
| microsoft | sharepoint_server | 2016 |
| microsoft | sharepoint_server | 2019 |
Check a specific version with /api/v1/cve/match.
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55040
- https://github.com/sfewer-r7/CVE-2026-55040
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-55040
- https://www.rapid7.com/blog/post/ra-microsoft-sharepoint-jwt-token-authentication-bypass-cve-2026-55040/
Query this programmatically:
curl https://evil-db.io/api/v1/cve/CVE-2026-55040