CVE-2026-45156
Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC
CVSS Score
8.1
EPSS Score
0.0%
EPSS Percentile
9th
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.
| CWE | CWE-287 |
| Vendor | nextcloud |
| Product | security-advisories |
| Published | Jun 1, 2026 |
| Last Updated | Jun 3, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Affected Versions
nextcloud / security-advisories
>= 0.3.0, < 3.1.0 >= 5.0.0, < 5.1.0 >= 6.0.0, < 6.4.0