{"id":"CVE-2026-45156","state":"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.","publishedAt":"2026-06-01T16:38:46.470Z","updatedAt":"2026-06-03T03:55:47.564Z","severity":{"score":8.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["nextcloud security-advisories"],"affected":[{"vendor":"nextcloud","product":"security-advisories","versions":[{"version":">= 0.3.0, < 3.1.0","status":"affected"},{"version":">= 5.0.0, < 5.1.0","status":"affected"},{"version":">= 6.0.0, < 6.4.0","status":"affected"}]}],"references":["https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp","https://github.com/nextcloud/user_oidc/pull/1285","https://hackerone.com/reports/3489490"],"weaknesses":["CWE-287"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/45xxx/CVE-2026-45156.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-45156","state":"PUBLISHED","datePublished":"2026-06-01T16:38:46.470Z","dateUpdated":"2026-06-03T03:55:47.564Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-08T20:44:38.964Z"},"containers":{"cna":{"title":"Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"nextcloud","product":"security-advisories","versions":[{"version":">= 0.3.0, < 3.1.0","status":"affected"},{"version":">= 5.0.0, < 5.1.0","status":"affected"},{"version":">= 6.0.0, < 6.4.0","status":"affected"}]}],"references":[{"url":"https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp","name":"https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/nextcloud/user_oidc/pull/1285","name":"https://github.com/nextcloud/user_oidc/pull/1285","tags":["x_refsource_MISC"]},{"url":"https://hackerone.com/reports/3489490","name":"https://hackerone.com/reports/3489490","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":8.1,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-287","lang":"en","description":"CWE-287: Improper Authentication","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-06-01T16:38:46.470Z"},"source":{"advisory":"GHSA-qqgv-fqwp-mjpp","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-02T00:00:00+00:00","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3","id":"CVE-2026-45156"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-03T03:55:47.564Z"}}]}}}