CVE-2026-45156

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

Published Jun 1, 2026 CVSS 3.1 · 8.1 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Nextcloud
Nextcloud user Oidc
Vendors & Products Nextcloud
Nextcloud user Oidc
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC
Weaknesses CWE-287
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jun 3, 2026, 3:55 AM
Reserved
May 8, 2026, 8:44 PM
Status
Deferred
Published
Jun 1, 2026, 5:17 PM
Modified
Jul 22, 2026, 7:10 AM