{"id":"CVE-2026-75628","title":"Punk::OAuth2 versions before 0.03 for Perl allow an attacker-chosen off-site redirect after login because same_origin_path accepts a backslash or tab in the return parameter","summary":"Punk::OAuth2 versions before 0.03 for Perl allow an attacker-chosen off-site redirect after login because same_origin_path accepts a backslash or tab in the return parameter.\n\noauth2_login reads the return parameter from the initiation r…","severity":"medium","cvss":5.7,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N","cvssSource":"adp","cwe":["CWE-601"],"product":"Punk-OAuth2","affected":["Punk-OAuth2 < 0.03"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-08-28T15:11:05.001417Z"},"published":"2026-08-20","updated":"2026-10-19","sourceUpdated":"2026-10-19T21:19:28.700Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-75628","references":[{"url":"https://metacpan.org/release/LNATION/Punk-OAuth2-0.03/changes"},{"url":"https://metacpan.org/release/LNATION/Punk-OAuth2-0.02/source/include/pox/pox_util.h#L94"},{"url":"https://datatracker.ietf.org/doc/html/rfc9700#section-4.11.1"},{"url":"https://url.spec.whatwg.org/#relative-slash-state"},{"url":"https://url.spec.whatwg.org/#concept-basic-url-parser"}],"tags":["cve.org"],"epss":0.00503,"epssPercentile":0.41754,"ingestedAt":"2026-10-19T21:43:56.120Z","slug":"CVE-2026-75628","body":"## Overview\n\nPunk::OAuth2 versions before 0.03 for Perl allow an attacker-chosen off-site redirect after login because same_origin_path accepts a backslash or tab in the return parameter.\n\noauth2_login reads the return parameter from the initiation request, runs same_origin_path over it, and stores the survivor in the session flow record as the post-login redirect target. That check rejects a value that does not begin with a slash, one with a slash as its second byte, and one containing CR or LF. A backslash and a tab pass. The URL Standard treats a backslash as equivalent to a slash for special schemes, so `/\\evil.example` parses with the authority `evil.example`. It also strips ASCII tab before parsing, so a tab between two leading slashes leaves `//evil.example`.\n\nA crafted link to the application's own login route lands the victim on the attacker's site after a genuine authentication. The redirect carries no authorization code or access token.\n\n## Affected\n\n- `Punk-OAuth2 < 0.03`\n\n## Remediation\n\nUpgrade to Punk-OAuth2 0.03 or later.\n\n### Workarounds\n\nFor deployments that cannot upgrade to 0.03, strip the return query parameter from requests to the oauth2_login initiation route at the reverse proxy. Logins then use the configured redirect_ok destination.","depth":"sunlit","depthScore":31,"depthScoreParts":{"impact":31.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}