CVE-2026-45156

HIGH

Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC

Title source: cna
STIX 2.1

Description

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.

References (3)

Core 3
Core References
X_Refsource_Misc x_refsource_misc
https://github.com/nextcloud/user_oidc/pull/1285
X_Refsource_Misc x_refsource_misc
https://hackerone.com/reports/3489490

Scores

CVSS v3 8.1
EPSS 0.0031
EPSS Percentile 22.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-287
Status published
Products (3)
nextcloud/security-advisories >= 0.3.0, < 3.1.0
nextcloud/security-advisories >= 5.0.0, < 5.1.0
nextcloud/security-advisories >= 6.0.0, < 6.4.0
Published Jun 01, 2026
Tracked Since Jun 01, 2026