Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC
Priority LOW 37CWE-287Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-287.
Summary
Nextcloud is an open source content collaboration platform. From versions 0.3.0 to before 3.1.0, 5.0.0 to before 5.1.0, and 6.0.0 to before 6.4.0, a missing signature verification in User OIDC allowed a malicious ID4me authority to identify as any user. This issue has been patched in versions 3.1.0, 4.1.0, 5.1.0, 6.4.0 and 8.3.0.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00412 35th percentileScored 2026-11-07
Fix Fixed security-advisories (nextcloud): 3.1.0, 5.1.0, 6.4.0
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| nextcloud | security-advisories | 0.3.0 to before 3.1.0; 5.0.0 to before 5.1.0; 6.0.0 to before 6.4.0 | 3.1.0, 5.1.0, 6.4.0 | Patch available | CNA |
- security-advisories Vendornextcloud Affected 0.3.0 to before 3.1.0; 5.0.0 to before 5.1.0; 6.0.0 to before 6.4.0 Fixed in 3.1.0, 5.1.0, 6.4.0 Patch available CNA
Remediation
- Fix · CNA security-advisories (nextcloud) Fixed in 3.1.0, 5.1.0, 6.4.0
Timeline
- 2026-10-02 Threatist record created from CVE-2026-45156
References
More nextcloud vulnerabilities
- TI-2026-18211 Windmill < 1.615.0 Operator Role Missing Authorization Checks RCE CVSS 4.0HIGH 8.7
- TI-2023-14838 NextCloud Cookbook's pull-checks.yml workflow is vulnerable to OS Command Injection CVSS 3.1HIGH 8.8
- TI-2022-08650 Command Injection in Appointment Emails for Nextcloud Calendar CVSS 3.1CRITICAL 9.8
- TI-2023-20855 Users can delete external storage mount points CVSS 3.1HIGH 7.7
- TI-2023-11091 Nextcloud download permissions can be changed by resharer CVSS 3.1HIGH 7.5
- TI-2023-10624 Nextcloud Server vulnerable to SSRF via filter bypass due to lax checking on IPs CVSS 3.1MEDIUM 5.3
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences