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Fencer Vulns
medium 6.8

CVE-2026-58404 json

Hugo security.http.urls deny rules bypassed by alternate IPv4 encodings

published 2026-06-19 4 mo ago modified 2026-10-25 14 d ago also GHSA-r46f-3rpw-hxrv , GO-2026-5606 , EUVD-2026-41918

cvss
6.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/gohugoio/hugo 0.163.1
  • gohugo hugo 0.163.1
  • hugo Debian 14 0.165.0-1

debian advisories DEBIAN-CVE-2026-58404

  • hugo hummingbird 1 0.163.3-0.1.hum1

red hat advisories RHSA-2026:36862

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-58404 updated cvss 6.8

github.com/gohugoio/hugo: Hugo: Server-Side Request Forgery (SSRF) via alternate IPv4 encodings

  • Red Hat Hardened Images hugo 0.163.3-0.1.hum1
    fixed: vendor fix RHSA-2026:36862

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 4.6 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
CNA 4.0 4.6 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 6.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
go github.com/gohugoio/hugo
>=0.162.0, <0.163.1
0.163.1

Affected products

  • gohugoio hugo

Classification

Weakness
  • CWE-918 Server-Side Request Forgery

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.