{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-45156", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-05-08T20:44:38.964Z", "datePublished": "2026-06-01T16:38:46.470Z", "dateUpdated": "2026-06-01T18:12:59.272Z"}, "containers": {"cna": {"title": "Nextcloud: Authentication Bypass in ID4me handling via Missing JWT Signature Verification in User OIDC", "problemTypes": [{"descriptions": [{"cweId": "CWE-287", "lang": "en", "description": "CWE-287: Improper Authentication", "type": "CWE"}]}], "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"}}], "references": [{"name": "https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp"}, {"name": "https://github.com/nextcloud/user_oidc/pull/1285", "tags": ["x_refsource_MISC"], "url": "https://github.com/nextcloud/user_oidc/pull/1285"}, {"name": "https://hackerone.com/reports/3489490", "tags": ["x_refsource_MISC"], "url": "https://hackerone.com/reports/3489490"}], "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"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-06-01T16:38:46.470Z"}, "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."}], "source": {"advisory": "GHSA-qqgv-fqwp-mjpp", "discovery": "UNKNOWN"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-06-01T18:12:50.808465Z", "id": "CVE-2026-45156", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-01T18:12:59.272Z"}}]}}

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{"cveTags": [], "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."}], "id": "CVE-2026-45156", "lastModified": "2026-06-01T18:14:29.087", "metrics": {"cvssMetricV31": [{"cvssData": {"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"}, "exploitabilityScore": 2.8, "impactScore": 5.2, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-06-01T17:17:09.283", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/nextcloud/security-advisories/security/advisories/GHSA-qqgv-fqwp-mjpp"}, {"source": "security-advisories@github.com", "url": "https://github.com/nextcloud/user_oidc/pull/1285"}, {"source": "security-advisories@github.com", "url": "https://hackerone.com/reports/3489490"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-287"}], "source": "security-advisories@github.com", "type": "Primary"}]}

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