Critical CVSS 9.1 Actively exploited
CVE-2026-55040
Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.
What this means
- Exposure
- Exploitable remotely over the network, without authentication and with no action from the victim.
- Impact
- An attacker can read sensitive data and modify or destroy data.
- Likelihood
- Exploitation is not hypothetical: CISA has observed it in the wild.
What to doTop priority: CISA sets the remediation deadline at 21 August 2026. Start with the instances exposed to the internet.
Read automatically from the CVSS vector, the weakness type (CWE) and the EPSS score. The technical description above remains the one published by NIST.