CVE-2026-55040Bypass de seguridad en Microsoft SharePoint
Microsoft SharePoint contains a weak authentication vulnerability which allows an unauthorized attacker to bypass a security feature over a network.
Ver en NVDAnálisis
Microsoft SharePoint Server presenta una debilidad en su sistema de autenticación que permite a atacantes no autorizados evadir funciones de seguridad a través de la red. Esta vulnerabilidad está siendo explotada activamente en ataques reales para comprometer entornos corporativos. Se recomienda a los equipos de infraestructura y backend actualizar sus servidores Windows de inmediato.
Roles relevantes
Severidad
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NCWE-1390CISA KEV
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.
EPSS
Afecta
microsoft:sharepoint_serverDescripción técnica
Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.
Referencias
- 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/