PT-2026-53796 · Go · Github.Com/Gohugoio/Hugo
Published
2026-06-19
·
Updated
2026-06-19
CVSS v4.0
7.7
High
| Vector | AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N |
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).
Fix
SSRF
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Weakness Enumeration
Related Identifiers
Affected Products
Github.Com/Gohugoio/Hugo