{"id":"CVE-2026-18918","summary":"OAuth 1.0 session-fixation chain via unauthenticated provisional-consumer registration and insecure v1_0Allowed default","details":"In Eclipse Lyo versions 2.0.0 to 7.0.0, OAuth server authorization checks can be bypassed when the 2-legged auth is supported by the server. In those cases, application that based their authz filters upon Lyo-provided `AbstractAdapterCredentialsFilter`, are vulnerable. An attacked can create a provisional trusted client (valid use-case) but then it can be used as a trusted client immediately without requiring the administrator approval to clear the provisional status. The 3-legged path requiring user interaction is not vulnerable and rejects provisional clients.","modified":"2026-09-01T03:30:51.250436144Z","published":"2026-08-28T08:54:07.990Z","database_specific":{"cwe_ids":["CWE-863"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18918.json","unresolved_ranges":[{"extracted_events":[{"introduced":"2.0.0"},{"fixed":"7.0.0"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"eclipse"},"references":[{"type":"WEB","url":"https://github.com/eclipse-lyo/lyo/releases/tag/v6.0.1.Final"},{"type":"WEB","url":"https://github.com/eclipse-lyo/lyo/releases/tag/v7.0.0.Beta3"},{"type":"WEB","url":"https://gitlab.eclipse.org/security/cve-assignment/-/work_items/221"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18918.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-18918"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/eclipse-lyo/lyo","events":[{"introduced":"0"},{"fixed":"b2aea6146e62e1f292aff2b5ab65086e9c82b1a5"}],"database_specific":{"source":"REFERENCES"}}],"versions":["v6.0.1.Alpha1","v6.0.0.Final","v6.0.0.CR","v6.0.0.Beta","6.0.0.Beta","v6.0.0.Alpha1","v5.1.1.Final","v5.1.0","v5.1.0-alpha","v5.0.0","v5.0.0.CR","v5.0.0.alpha4","v5.0.0.alpha3","v5.0.0.alpha2","v5.0.0.alpha1","v4.1.0","v4.1.0.RC","v4.1.0.M1","v4.1.0.alpha1","v4.0.0","v4.0.0.RC"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-18918.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/AU:Y/R:U/V:C/RE:L/U:Red"}]}