CVE-2026-58404

Hugo is a static site generator. From v0.162.0 through v0.163.0, the default security.http.urls policy denies requests to loopback, internal, and cloud-metadata IPv4 literals, but the deny rule only matched dotted-decimal notation, so alternate IPv4 encodings of the same addresses, including integer, hex, or octal, passed the policy. When a template passes an untrusted or data-derived URL to resources.GetRemote and the host platform uses the cgo system resolver, these encodings resolve to the blocked address, allowing build-time server-side requests to loopback and internal services, including the cloud-metadata endpoint in hosted or CI builds; the same check is reused on redirects, so the gap also applies to each redirect hop. This issue is fixed in v0.163.1.

• github.comhttps://github.com/gohugoio/hugo/commit/a00b5c72ac57afe26df6688ece3ca544a56df372
• github.comhttps://github.com/gohugoio/hugo/pull/15020
• github.comhttps://github.com/gohugoio/hugo/releases/tag/v0.163.1
• github.comhttps://github.com/gohugoio/hugo/security/advisories/GHSA-r46f-3rpw-hxrv