Status: KEV | Advisory ID: CVE-2026-55040
| CVE | CVE-2026-55040 |
| CVSS | CVSS 9.1 (Critical). |
| Affected products | Microsoft SharePoint and Microsoft SharePoint Server |
| Exploitation status | Listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating confirmed active exploitation. |
| Classified as | CWE-1390 (Weak Authentication) |
| KEV listing | Added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-08-18. |
| Exploitation prediction (EPSS) | 51% probability of exploitation in the next 30 days (99% percentile) -- FIRST.org's EPSS model. |
| Federal remediation deadline | 2026-08-21 (CISA KEV, Binding Operational Directive). |
Microsoft SharePoint contains a weak authentication vulnerability which allows an unauthorized attacker to bypass a security feature over a network.
| Source | Reference |
|---|---|
| NVD | https://nvd.nist.gov/vuln/detail/CVE-2026-55040 |