Hugo: security.http.urls deny rules bypassed by alternate IPv4 encodings (SSRF)GHSA-r46f-3rpw-hxrv
GHSA-r46f-3rpw-hxrv is a Server-Side Request Forgery (SSRF) vulnerability in github.com/gohugoio/hugo. A fix is available for github.com/gohugoio/hugo — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-r46f-3rpw-hxrv.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
github.com/gohugoio/hugoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Impact
The default security.http.urls policy denies requests to loopback, internal,
and cloud-metadata IPv4 literals (e.g. http://127.0.0.1/,
http://169.254.169.254/). The deny rule only matched dotted-decimal notation,
so alternate IPv4 encodings of the same addresses — integer, hex, or octal,
which contain no dot — passed the policy:
http://2130706433/→127.0.0.1http://2852039166/→169.254.169.254(cloud metadata)http://0x7f000001/,http://017700000001/,http://0/
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/CI builds. The same check is reused on
redirects, so the gap also applies to each redirect hop.
This affects sites that rely on security.http.urls as a security boundary
while fetching attacker-influenced remote URLs; it does not affect sites that
fully trust the URLs they fetch.
Patches
Fixed in v0.163.1. Integer/hex/octal IPv4 hosts are now canonicalized to dotted-decimal before the policy is applied, so every encoding of an address is treated alike. No configuration change is required.
Workarounds
Avoid passing untrusted URLs to resources.GetRemote, or
tighten security.http.urls to an explicit allow-list of trusted hosts.
Affected versions
v0.162.0 – v0.163.0 (patched in v0.163.1).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/gohugoio/hugo | ≥ 0.162.0&&< 0.163.1 | 0.163.1go get github.com/gohugoio/hugo@v0.163.1 |
Affected Products
hugogohugoDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gohugoio/hugo, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/gohugoio/hugo to 0.163.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r46f-3rpw-hxrv is resolved across your whole dependency graph.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Hardened Images | hugo-main-0.163.3-0.1.hum1 | RHSA-2026:36862 |
Frequently Asked Questions
Is GHSA-r46f-3rpw-hxrv in your dependencies?
Find it across Go, including transitive dependencies.