{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/concourse/concourse"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.6.1-0.20260526150512-ac60be5f0435"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-49826"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-601"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-01T19:01:16Z",
    "nvd_published_at": null,
    "severity": "LOW"
  },
  "details": "### Impact\n\nAn attacker is able to craft and send a user a URL that will redirect the user from the Concourse web server to any other site. This could be used in a phishing attack to steal user\u0027s credentials.\n\n### Patches\n\nThis has been fixed in 8.2.3\n\n### Workarounds\n\nNone.\n\n### Exploit\n\nVulnerable code was in: https://github.com/concourse/concourse/blob/ea7b812e3a88fdd070f0faece874e8a2d4fbb31c/skymarshal/skyserver/skyserver.go#L162-L170\n\nThe issue stems from the underlying processing logic of Go\u0027s `url` package. Normally, `ParseRequestURI()` will eventually reach an internal `url.setPath()` function, where the URL will be decoded. However, if `RawPath` is not empty and `validEncoded(RawPath)` is true, and the decoded result equals `Path`, then return `RawPath` as is; otherwise, escape `Path` again, i.e., decode it again.\n\nIn other words, if the URL contains dangerous characters that should be escaped, such as backslashes (`\\`), then an extra decoding step will be performed. Therefore, `/%2Fexample.com` will be parsed as `//example.com`.\n\nOn vulnerable versions of Concourse, add `/sky/login?redirect_uri=/%252Fexample.com/\\` to your Concourse external URL, login as usual, and you should be redirected to `example.com` instead of your Concourse web server. The redirect happens after the login flow completes. No credentials are leaked.",
  "id": "GHSA-8w27-c4vc-88q9",
  "modified": "2026-07-01T19:01:16Z",
  "published": "2026-07-01T19:01:16Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/concourse/concourse/security/advisories/GHSA-8w27-c4vc-88q9"
    },
    {
      "type": "WEB",
      "url": "https://github.com/concourse/concourse/commit/ac60be5f0435b6592f5a4fcc089050d72ad2452c"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/concourse/concourse"
    },
    {
      "type": "WEB",
      "url": "https://github.com/concourse/concourse/releases/tag/v8.2.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Concourse login flow has an open redirect issue"
}