criticalKEV
CVE-2026-55040
SharePoint Server JWT authentication bypass - an unsigned (alg:none) Bearer token authenticates an anonymous caller on /_api/* (CVSS 9.1)
- Severity
- critical
- Affected product
- Microsoft SharePoint Server
- Affected versions
- Microsoft SharePoint Server all versions before the fix
- Detection basis
- Appliance fingerprint
- Shipped rule
- Microsoft SharePoint Server: SharePoint Server JWT authentication bypass - an unsigned (alg:none) Bearer token authenticates an anonymous caller on /_api/* (CVSS 9.1)
- CISA KEV
- Listed as a known exploited vulnerability
- EPSS
- 4% chance of exploitation in the next 30 days
- Added to NewScan
- 2026-08-19
- Detected by
- NewScan — free, self-hosted
How NewScan reports it
APPLIANCE FINGERPRINT
NewScan fingerprints the Microsoft SharePoint Server appliance and reports this CVE when the detected version falls inside the affected range below.
References
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