{"id":"CVE-2026-58404","aliases":["GHSA-r46f-3rpw-hxrv","GO-2026-5606"],"url":"https://o3.security/vulnerability/CVE-2026-58404","summary":"Hugo security.http.urls deny rules bypassed by alternate IPv4 encodings","details":"### Impact\n\n  The default `security.http.urls` policy denies requests to loopback, internal,\n  and cloud-metadata IPv4 literals (e.g. `http://127.0.0.1/`,\n  `http://169.254.169.254/`). The deny rule only matched dotted-decimal notation,\n  so alternate IPv4 encodings of the same addresses — integer, hex, or octal,\n  which contain no dot — passed the policy:\n\n  - `http://2130706433/` → `127.0.0.1`\n  - `http://2852039166/` → `169.254.169.254` (cloud metadata)\n  - `http://0x7f000001/`, `http://017700000001/`, `http://0/`\n\n  When a template passes an untrusted or data-derived URL to\n  `resources.GetRemote` and the host platform uses the\n  cgo system resolver, these encodings resolve to the blocked address — allowing\n  build-time server-side requests to loopback and internal services, including the\n  cloud-metadata endpoint in hosted/CI builds. The same check is reused on\n  redirects, so the gap also applies to each redirect hop.\n\n  This affects sites that rely on `security.http.urls` as a security boundary\n  while fetching attacker-influenced remote URLs; it does not affect sites that\n  fully trust the URLs they fetch.\n\n  ### Patches\n\n  Fixed in **v0.163.1**. Integer/hex/octal IPv4 hosts are now canonicalized to\n  dotted-decimal before the policy is applied, so every encoding of an address is\n  treated alike. No configuration change is required.\n\n  ### Workarounds\n\n  Avoid passing untrusted URLs to `resources.GetRemote`, or\n  tighten `security.http.urls` to an explicit allow-list of trusted hosts.\n\n  ### Affected versions\n\n  v0.162.0 – v0.163.0 (patched in v0.163.1).","published":"2026-07-06T19:16:15.945Z","modified":"2026-10-21T02:31:06.645019406Z","cvss":null,"epss":{"score":0.00368,"percentile":0.30439,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/gohugoio/hugo","fixedVersion":"0.163.1"}],"fix":{"url":"https://github.com/gohugoio/hugo/commit/a00b5c72ac57afe26df6688ece3ca544a56df372","label":"gohugoio/hugo@a00b5c7"},"references":[{"type":"WEB","url":"https://github.com/gohugoio/hugo/releases/tag/v0.163.1"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/58xxx/CVE-2026-58404.json"},{"type":"ADVISORY","url":"https://github.com/gohugoio/hugo/security/advisories/GHSA-r46f-3rpw-hxrv"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-58404"},{"type":"FIX","url":"https://github.com/gohugoio/hugo/commit/a00b5c72ac57afe26df6688ece3ca544a56df372"},{"type":"FIX","url":"https://github.com/gohugoio/hugo/pull/15020"},{"type":"PACKAGE","url":"https://github.com/gohugoio/hugo"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:31:06.645019406Z"}}