CVE-2026-45156 HIGH

CVE-2026-45156: Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC

Vendor Nextcloud
Product security-advisories
Weakness CWE-287 · Improper authentication
Published June 1, 2026
Last update June 3, 2026
View on NVD All CVEs

CVSS base score

8.1/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction Required
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

June 1, 2026 CVE published
June 3, 2026 Record updated