CVE-2026-58404
MediumCVSS 6.8Exploitation Probability (EPSS)
Low risk11th percentile - higher than 11% of all known CVEs
Summary
A vulnerability in Hugo from v0.162.0 to v0.163.0 allows bypassing the security policy that blocks requests to loopback, internal, and cloud-metadata IPv4 addresses. The policy only matched dotted-decimal notation, so alternative IPv4 encodings (integer, hex, octal) bypassed the block. When a template passes an untrusted URL to resources.GetRemote and the host uses the cgo system resolver, these encodings resolve to blocked addresses, enabling SSRF attacks to internal services and cloud-metadata endpoints in hosted or CI builds.
Risk Assessment
An attacker can exploit this vulnerability to perform Server-Side Request Forgery (SSRF) attacks against internal services or cloud-metadata endpoints, potentially leading to data exfiltration, privilege escalation, or compromise of the build environment.
Recommendation
Upgrade Hugo to version v0.163.1 or later immediately, which fixes the issue. Additionally, review templates for passing untrusted data to the resources.GetRemote function.
Original NVD description (English source)
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.