{"id":"GHSA-xxhq-69mf-w8cr","summary":"Gogs has an Open Redirect via redirect_to","details":"### Summary\nAn open redirect vulnerability exists in Gogs where attacker-controlled `redirect_to` parameters can bypass validation, allowing redirection to arbitrary external sites.\n\n\n### Details\nAll redirects in Gogs that are validated via the `IsSameSite` function are vulnerable:\n```go\nfunc IsSameSite(url string) bool {\n    return len(url) \u003e= 2 && url[0] == '/' && url[1] != '/' && url[1] != '\\\\'\n}\n```\n\nThe function only inspects the first two characters of the URL string. This check fails to account for directory traversal sequences followed by backslashes. For example:\n```\n/a/../\\example.com\n```\n\nThe `IsSameSite` function checks the input supplied to the `redirect_to` query parameter value `/a/../\\example.com` and considers it valid.\n\nBecause web browsers normalize backslashes `\\` to forward slashes `/`, the normalized URL becomes `//example.com`.\n\nThe normalized URL becomes:\n```\n//example.com\n```\n\nResulting in a cross-origin redirect.\n\nThis affects all endpoints using the `redirect_to` query parameter, including login and other post-action flows.\n\n\n### PoC\n\n1. An attacker can provide a user with a link to login to Gogs with a `redirect_to` query parameter that redirects a user to a site the attacker wants them to visit:\n```\nhttp://192.168.236.132:3000/user/login?redirect_to=/a/../\\example.com\n```\n\n\u003cimg width=\"1339\" height=\"536\" alt=\"image\" src=\"https://github.com/user-attachments/assets/3c2a13b8-f0b7-42c2-a223-6f0ebf083589\" /\u003e  \n\n\u003cbr\u003e\n\u003cbr\u003e\n\n2. After the user successfully logs in, they would be redirected to the site an attacker wants them to visit:\n\n\u003cimg width=\"1066\" height=\"463\" alt=\"image\" src=\"https://github.com/user-attachments/assets/1726a3d9-6705-43cc-bdd2-90aad105d021\" /\u003e\n\n\u003cimg width=\"1097\" height=\"396\" alt=\"image\" src=\"https://github.com/user-attachments/assets/376052f5-0e00-4d14-a548-fa75a6269530\" /\u003e\n\n\n### Impact\n* Phishing: Attackers can use trusted domain links to redirect victims to credential-harvesting pages\n* OAuth/SSO Token Theft: In authentication flows, authorization codes or tokens may leak via redirect\n* Referer Leakage: Sensitive URL parameters may be exposed to attacker domains via the Referer header\n* Cache Poisoning: In deployments with shared caches, malicious redirects may be cached and served to other users","aliases":["CVE-2026-52802","GO-2026-5773"],"modified":"2026-07-21T13:45:23.442166157Z","published":"2026-06-23T16:42:02Z","database_specific":{"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-06-23T16:42:02Z","nvd_published_at":"2026-06-24T21:16:56Z","cwe_ids":["CWE-601"]},"references":[{"type":"WEB","url":"https://github.com/gogs/gogs/security/advisories/GHSA-xxhq-69mf-w8cr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52802"},{"type":"WEB","url":"https://github.com/gogs/gogs/pull/8322"},{"type":"WEB","url":"https://github.com/gogs/gogs/commit/c5da9631dc75f692f313373ae229c4d47ba6517f"},{"type":"PACKAGE","url":"https://github.com/gogs/gogs"},{"type":"WEB","url":"https://github.com/gogs/gogs/releases/tag/v0.14.3"}],"affected":[{"package":{"name":"gogs.io/gogs","ecosystem":"Go","purl":"pkg:golang/gogs.io/gogs"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.14.3"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 0.14.2","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-xxhq-69mf-w8cr/GHSA-xxhq-69mf-w8cr.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N"}]}