Threat Intelligence Database

Hugo versions from v0.162.0 before v0.166.0 contain a case-sensitive validation flaw in the security.http.urls IP-literal deny rule that allows attackers to bypass restrictions. Attackers can use mixed-case URL schemes in resources.GetRemote calls to fetch from restricted IP addresses like localhost.

Hugo is a static site generator. In versions after v0.123.0 and before v0.166.0, Hugo's symlink confinement checks stopped at the mount root itself, so a theme or module checked into themes/ (or a vendored module) could contain a symlink at a mount root (for example themes/mytheme/assets -> /some/dir/outside). Files behind such a symlink were readable during a site build through resources.Get, resources.Match and similar functions, and could be published to public/ via static mounts, bypassing the rule that theme and module mount sources must be local paths. Modules fetched via Go modules are not affected because Go module zips cannot contain symlinks, and this is not an escalation for the main project, which may already mount absolute paths by configuration. Fixed in v0.166.0, where symlinked mount roots and symlinked directories between the mount root and the module directory are treated as non-existent for all modules. As a workaround, inspect themes/ and vendored modules for symlinks at mount roots before building, or replace symlinks with explicit mounts.

Hugo versions 0.75.0 through 0.165.x contain a stored cross-site scripting vulnerability: the syntax highlighter does not escape the `lineAnchors` option before passing it to Chroma, which writes the value verbatim into the `id` and `href` attributes of the generated line-number markup. A crafted `lineAnchors` value supplied as a Markdown code fence attribute (or passed to the `highlight` template function) results in unescaped HTML in the rendered page, allowing arbitrary JavaScript to execute in the browsers of visitors to the generated site. This affects sites that build and publish Markdown from untrusted contributors; Hugo's security model otherwise considers content trusted input. Fixed in 0.166.0, where the `lineAnchors` value is HTML-escaped before being passed to Chroma.

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.

Hugo is a static site generator. In versions after v0.123.0 and before v0.165.0, symlinks in parent directories were not dropped during direct resource lookups, allowing path confinement to be bypassed. An attacker who can place — or who convinces a site author to place — a symlink inside a mounted directory (for example, in a locally vendored theme under themes/) can cause functions that perform direct lookups, such as resources.Get and os.ReadFile, to follow that symlink and read files outside the intended project boundaries, disclosing their contents in the built site. Themes mounted as Go modules fetched from GitHub have symlinks stripped on download and are not affected, and multi-directory walks (e.g. content/asset walking) are not affected. This issue is an incomplete-fix follow-up to GHSA-c3wq-j5vh-68rc and GHSA-fw87-fv5r-9fpw; it is fixed in v0.165.0.

Hugo is a static site generator. From 0.123.0 to 0.161.1, a regression made  RootMappingFs.statRoot  use  Stat  (follows symlinks) instead of  Lstat , so a direct  resources.Get  of a symlink pointing outside its mount returned the target's contents — letting a symlink planted in a local mount (e.g. a vendored  themes/  theme) read arbitrary files accessible to the Hugo user. Go-module themes from GitHub (symlinks stripped) and directory walks were unaffected. Fixed in 0.162.0.

Hugo is a static site generator. From 0.91.0 until 0.162.0, resources.GetRemote enforces security.http.urls on the URL it is called with, but it did not re-validate intermediate URLs on HTTP 3xx redirects. An allowed server (or an attacker controlling its DNS or response) could therefore redirect the request to a host that the policy was meant to forbid and Hugo would fetch from the redirected target. The same bypass also lifted any host-shape restriction the operator had put in place. This vulnerability is fixed in 0.162.0.

Hugo is a static site generator. Prior to 0.162.0, Hugo accepts content files in several markup formats. Files mapped to the text/html media type (typically .html files under /content, or pages produced by a content adapter that sets content.mediaType = "text/html") had their body emitted verbatim into the rendered page. A site that ingests HTML content from an untrusted source could therefore be served stored cross-site scripting. This vulnerability is fixed in 0.162.0.

Hugo is a static site generator. From v0.123.0 through v0.163.0, Hugo's virtual filesystem is designed so that files under a mount cannot reach outside the mount tree, but a regression caused RootMappingFs.statRoot to call Stat, which follows symlinks, instead of Lstat, so a direct os.ReadFile "somefile" where somefile was a symlink pointing outside the mount would return the target's contents. This effectively let a symlink planted inside a theme or local mount read arbitrary files reachable to the user running hugo. This issue is fixed in v0.163.1.

Hugo is a static site generator. From 0.60.0 until 0.163.3, Hugo's default code-block renderer wrote the Markdown code-fence language or info-string into the code class="language-…" data-lang="…" wrapper without HTML escaping. A fence info-string containing a quote and a script payload breaks out of the attribute and injects a live script element. This issue is fixed in 0.163.3.