{"id":"CVE-2026-54603","aliases":["GHSA-pp92-crg2-gfv9"],"url":"https://o3.security/vulnerability/CVE-2026-54603","summary":"OAuth2::Client#request: Protocol-relative redirect Location overrides authority, leaking bearer Authorization to attacker host","details":"OAuth2 is a Ruby wrapper for the OAuth 2.0 and 2.1 authorization frameworks, including OpenID Connect (OIDC). From 0.4.0 to 2.0.21, a protocol-relative redirect Location returned to OAuth2::Client#request overrides the request authority, so the bearer Authorization header is sent to an attacker-controlled host, leaking the credential. This issue is fixed in version 2.0.22.","published":"2026-07-28T16:29:03.566Z","modified":"2026-09-11T03:48:28.253608206Z","cvss":{"score":8.6,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N"},"epss":{"score":0.00434,"percentile":0.36707,"asOf":"2026-09-12"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"RubyGems","name":"oauth2","fixedVersion":"2.0.22"}],"fix":{"url":"https://github.com/ruby-oauth/oauth2/commit/0f0a474f1b38453e119e660c2daca742d4378ce9","label":"ruby-oauth/oauth2@0f0a474"},"references":[{"type":"WEB","url":"https://github.com/ruby-oauth/oauth2/releases/tag/v2.0.22"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54603.json"},{"type":"ADVISORY","url":"https://github.com/ruby-oauth/oauth2/security/advisories/GHSA-pp92-crg2-gfv9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54603"},{"type":"FIX","url":"https://github.com/ruby-oauth/oauth2/commit/0f0a474f1b38453e119e660c2daca742d4378ce9"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-11T03:48:28.253608206Z"}}