{"id":"CVE-2026-52802","title":"Gogs has an Open Redirect via redirect_to","summary":"Gogs has an Open Redirect via redirect_to","severity":"medium","cvss":5.4,"cwe":["CWE-601"],"vendor":"gogs","product":"gogs.io/gogs","ecosystem":"go","affected":["gogs.io/gogs <= 0.14.2"],"patched":["gogs.io/gogs 0.14.3"],"published":"2026-06-23","updated":"2026-06-23","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-xxhq-69mf-w8cr","references":[{"url":"https://github.com/gogs/gogs/security/advisories/GHSA-xxhq-69mf-w8cr"},{"url":"https://github.com/gogs/gogs/pull/8322"},{"url":"https://github.com/gogs/gogs/commit/c5da9631dc75f692f313373ae229c4d47ba6517f"},{"url":"https://github.com/gogs/gogs/releases/tag/v0.14.3"},{"url":"https://github.com/advisories/GHSA-xxhq-69mf-w8cr"}],"tags":["ghsa","go"],"epss":0.00554,"epssPercentile":0.44884,"ingestedAt":"2026-06-29T13:24:35.478Z","slug":"CVE-2026-52802","body":"## Overview\n\n### 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) >= 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<img width=\"1339\" height=\"536\" alt=\"image\" src=\"https://github.com/user-attachments/assets/3c2a13b8-f0b7-42c2-a223-6f0ebf083589\" />  \n\n<br>\n<br>\n\n2. After the user successfully logs in, they would be redirected to the site an attacker wants them to visit:\n\n<img width=\"1066\" height=\"463\" alt=\"image\" src=\"https://github.com/user-attachments/assets/1726a3d9-6705-43cc-bdd2-90aad105d021\" />\n\n<img width=\"1097\" height=\"396\" alt=\"image\" src=\"https://github.com/user-attachments/assets/376052f5-0e00-4d14-a548-fa75a6269530\" />\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\n\n## Affected packages\n\n- `gogs.io/gogs <= 0.14.2`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `gogs.io/gogs 0.14.3`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":29.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}