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OpenAdvisories
Medium · 4.6 CVE-2026-58404 EUVD-2026-41918GHSA-r46f-3rpw-hxrvGO-2026-5606

Hugo security.http.urls deny rules bypassed by alternate IPv4 encodings

Published Jul 6, 2026 · Updated Jul 7, 2026 · Assigned by GitHub_M

Description

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.

Affected products

VendorProductAffectedFixed
gohugoio hugo >= v0.162.0, < v0.163.1 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 hugo 0.165.0-1 —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 hugo No fix yet —
Ubuntu 26.04 LTS hugo No fix yet —
Ubuntu 25.10 hugo No fix yet —
Ubuntu 22.04 LTS hugo No fix yet —
Ubuntu 20.04 LTS hugo No fix yet —
Show 3 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 18.04 LTS hugo No fix yet —
Ubuntu 16.04 LTS hugo No fix yet —
Ubuntu Pro 24.04 LTS hugo No fix yet —
ReleasePackageFixed inAdvisory
Red Hat Hardened Images 1 hugo 0.163.3-0.1.hum1 RHSA-2026:36862

Affected packages

EcosystemPackageAffectedFixedRecord
Go github.com/gohugoio/hugo >= 0.162.0, < 0.163.1 0.163.1 GHSA-r46f-3rpw-hxrv

Advisories 1

References