Executive brief
Hugo is a static site generator that converts content files into websites. In affected versions, content files marked as Org Mode format can include unescaped HTML that executes in visitors' browsers, allowing attackers to inject malicious scripts. An attacker with the ability to create or modify content files can execute code on the websites of site visitors. The vulnerability only affects sites using Org Mode content and is fixed in version 0.166.0.
Technical details
The vulnerability is a stored cross-site scripting (XSS) flaw in Hugo's Org Mode content handler, where Org export blocks and @@html:...@@ snippets are rendered without HTML escaping. An attacker who can supply or influence content files under /content or via content adapters can inject arbitrary HTML and JavaScript that executes in visitor browsers. A fix is available in version 0.166.0, which introduces a security.allowContent allowlist denying text/org by default; sites using Org Mode content can opt back in with explicit configuration.
Affected products
- gohugoio Hugo v0.56.0 through v0.165.x
Timeline
- 2026-09-26: disclosed
- 2026-09-26: patched: Version 0.166.0 released with security.allowContent allowlist mitigation