CVE-2026-58404 Hugo security.http.urls deny rules bypassed by alternate IPv4 encodings
Attackers can bypass URL deny rules using alternate IPv4 encodings to access internal services or cloud metadata during Hugo builds.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-58404?
CVE-2026-58404 is a medium-severity server-side request forgery vulnerability in gohugoio hugo, published on 6 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-918
Which versions are affected by CVE-2026-58404?
3 open source packages ship an affected version, including github.com/gohugoio/hugo. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/gohugoio/hugo Go | From 0.162.0 | 0.163.1 |
github.com/gohugoio/hugo Go | From 0.162.0 | 0.163.1 |
github.com/gohugoio/hugo Go | From 0.162.0 | 0.163.1 |
Products include Gohugo Hugo.
How do I fix CVE-2026-58404?
Upgrade github.com/gohugoio/hugo to 0.163.1 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-58404 being exploited?
There is no known exploitation of CVE-2026-58404 in the wild and no public exploit code.
Other vulnerabilities in gohugoio hugo
- CVE-2026-75926 Hugo 0.162.0 to 0.164.x - Node Permission Model Bypass via Default TailwindCSS Child-Process Grant
- CVE-2026-100690 Hugo v0.161.0 to v0.165.0 Arbitrary File Read via Symlinks
- CVE-2026-100692 Hugo before v0.166.0 Path Traversal via Symlinked Mount Roots
- CVE-2026-100693 Hugo v0.162.0 before v0.166.0 IP-literal Deny Rule Bypass
- CVE-2020-26284 Hugo can execute a binary from the current directory on Windows
Sources
Also known as DEBIAN-CVE-2026-58404, GHSA-r46f-3rpw-hxrv, GO-2026-5606, UBUNTU-CVE-2026-58404.