{"id":"CVE-2026-45156","aliases":["EUVD-2026-33675","GHSA-qqgv-fqwp-mjpp"],"status":"published","title":"Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC","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.","severity":{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00412,"percentile":0.35771,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":false},"cwes":["CWE-287"],"published":"2026-06-01T16:38:46Z","modified":"2026-10-28T02:30:48Z","exploits":[{"source":"pocgithub","id":"cybertechajju/CVE-2026-45156-POC","title":"cybertechajju/CVE-2026-45156-POC","date":"2026-06-23","url":"https://github.com/cybertechajju/CVE-2026-45156-POC"}],"products":[{"vendor":"kiteworks","product":"security-advisories"},{"vendor":"nextcloud","product":"security-advisories"}],"references":[{"url":"https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp","tags":["x_refsource_CONFIRM","advisory"]},{"url":"https://github.com/nextcloud/user_oidc/pull/1285","tags":["x_refsource_MISC","fix"]},{"url":"https://hackerone.com/reports/3489490","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45156.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45156","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-45156","title":"Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC","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.","status":"published","published":"2026-06-01T16:38:46.47Z","modified":"2026-06-03T03:55:47.564Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T13:46:43.922571Z"}],"euvd":[{"id":"EUVD-2026-33675","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.","status":"published","published":"2026-06-01T16:38:46Z","modified":"2026-06-03T03:55:47Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T18:20:55.231104Z"}],"nvd":[{"id":"CVE-2026-45156","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.","status":"published","published":"2026-06-01T17:17:09.283Z","modified":"2026-07-22T07:10:00.107Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:12:21.635958Z"}],"osv":[{"id":"CVE-2026-45156","title":"Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC","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.","status":"published","published":"2026-06-01T16:38:46.47Z","modified":"2026-10-28T02:30:48.514900178Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T15:45:05.172514Z"}]}}