Hugo: security.http.urls deny rules bypassed by alternate IPv4 encodings (SSRF)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Impact The default security.http.urls policy denies requests to loopback, internal, and cloud-metadata IPv4 literals (e.g. http://127.0.0.1/, http://169.254.169.254/). The deny rule only matched dotted-decimal notation, so alternate IPv4 encodings of the same addresses — integer, hex, or octal, which contain no dot — passed the policy: - http://2130706433/ → 127.0.0.1 - http://2852039166/ → 169.254.169.254 (cloud metadata) - http://0x7f000001/, http://017700000001/, http://0/ 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/CI builds. The same check is reused on redirects, so the gap also applies to each redirect hop. This affects sites that rely on security.http.urls as a security boundary while fetching attacker-influenced remote…

Published by the source

19 Jun 2026, 19:18 UTC

Last modified by the source

19 Jun 2026, 19:18 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-r46f-3rpw-hxrv

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# Patch Next advisory brief: GHSA-r46f-3rpw-hxrv

Advisory: Hugo: security.http.urls deny rules bypassed by alternate IPv4 encodings (SSRF)
IDs: GHSA-r46f-3rpw-hxrv
Record: https://patchnext.com/advisories/ghsa-r46f-3rpw-hxrv (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/gohugoio/hugo 0.163.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/gohugoio/hugo: affected >= 0.162.0, < 0.163.1; fixed in 0.163.1

## Suggested inspection (read-only)
- Go github.com/gohugoio/hugo: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/gohugoio/hugo.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-r46f-3rpw-hxrv (GitHub-reviewed advisory GHSA-r46f-3rpw-hxrv lists affected ranges: Go github.com/gohugoio/hugo >=0.162.0 <0.163.1)

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