CVE-2026-100690: Hugo v0.161.0 to v0.165.0 Arbitrary File Read via Symlinks

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-26 · updated 2026-09-30
Weakness: CWE-59

Description

Hugo versions from v0.161.0 through v0.165.0 run Node.js tools (css.PostCSS, css.TailwindCSS, js.Babel) under the Node.js permission model to restrict file system reads to the project directory and configured mounts. Because the Node.js permission model validates only the lexical path and follows symbolic links that point outside the allowed set, Hugo did not detect symlinks escaping the sandbox. An attacker who can contribute content to a Hugo project (for example via a pull request) can commit a symlink such as assets/css/x.css -> /etc/passwd together with a PostCSS plugin that reads it, allowing any file readable by the Hugo build process to be disclosed and potentially embedded in the published site. This affects builds using the default security configuration; projects that do not invoke Node.js tools are unaffected. Fixed in v0.166.0, which scans allowed paths and fails the build when a symbolic link resolves outside them.

Affected products

gohugoio hugo: from 0.161.0 before 0.166.0 — fixed in 0.166.0

How to fix

Upgrade to a fixed version: gohugoio hugo 0.166.0. Check the vendor advisory for mitigations.

References

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