Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC
41Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 8.1epss 0.4%
from disclosure to weapon22 days
Published on NVDJun 1
1st PoC+22d
exploitation probability
0.4%top 66% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Affected products
nextcloud · security-advisoriespublic PoCs found — 1
githubgithub.com/cybertechajju/CVE-2026-45156-POC★ 2⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.