CVE-2026-58404
Hugo: security.http.urls deny rules bypassed by alternate IPv4 encodings (SSRF)
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.
How to fix CVE-2026-58404
To remediate CVE-2026-58404, upgrade the affected package to a fixed version below.
- —no fix listed
- —upgrade to 0.163.1 or later
Is CVE-2026-58404 being exploited?
Low — EPSS is 0.2%, meaning exploitation activity has not been observed at scale.
Affected packages (2)
- from 0
- >= 0.162.0, < 0.163.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |
| osv | CVSS 3.1 | MEDIUM6.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N |