CVE-2026-52802: Gogs.io/gogs Gogs Has An Open Redirect Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xxhq-69mf-w8cr",
  "modified" : "2026-07-21T13:36:21Z",
  "published" : "2026-06-23T16:42:02Z",
  "aliases" : [ "CVE-2026-52802" ],
  "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) >= 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",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "gogs.io/gogs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.14.3"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.14.2"
    }
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-601" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-23T16:42:02Z",
    "nvd_published_at" : "2026-06-24T21:16:56Z"
  }
}