Gohugoio vulnerabilities

Hugo from v0.60.0 before v0.167.0 contains a stored cross-site scripting vulnerability that allows Markdown content authors to inject HTML by supplying crafted explicit heading IDs. Attackers can break out of the unescaped href attribute in .TableOfContents or .Fragments.ToHTML output to inject elements with event handlers into rendered pages.

Hugo from v0.162.0 before v0.167.0 contains an improper link resolution vulnerability that lets malicious themes or modules expose files outside their root via nested-mount ancestor directories. Attackers controlling a theme can place a symlink or NTFS junction at a virtual ancestor directory, causing resources.Match to list and publish local files during builds.

Hugo from v0.84.0 before v0.167.0 contains a path traversal vulnerability that allows malicious themes or modules to read files outside the project root via ESBuild's fallback resolver in js.Build, js.Batch, and css.Build. Attackers can ship relative imports or symlinks pointing outside the project to bundle any file readable by the build user into published JavaScript or CSS output.

Hugo before v0.167.0 contains a path traversal vulnerability in css.Sass that allows malicious themes or modules to read files outside the project root through the Sass compiler's import fallback. Attackers can ship stylesheets with relative, absolute, or symlinked @import or @use targets to compile readable files into the published site CSS.

Hugo's default fenced-code-block renderer writes attribute values taken from the code-fence info string into the rendered HTML without escaping them. New in markup/internal/attributes/attributes.go converts every attribute value from a byte slice to a string as it is stored, deliberately dropping the escaping that used to happen there, and RenderAttributes in the same file escapes only values that are still byte slices, so its escaping branch is never reached and every value is written verbatim. The function's documentation states that it performs HTML escaping of string attributes, which it does not. A quote inside an attribute value in the info string therefore terminates the attribute and allows a further attribute, including an event handler, to be placed on the wrapper element, and the script runs for every visitor who loads the page. This path is reached under the default configuration, with code fences enabled and without goldmark's unsafe setting or any custom render hook. Attribute names beginning with on are filtered when the attributes are parsed, so injection is achieved through the value rather than the name.

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 v0.162.0 through v0.163.0, the default security.http.urls policy denies requests to loopback, internal, and cloud-metadata IPv4 literals, but the deny rule only matched dotted-decimal notation, so alternate IPv4 encodings of the same addresses, including integer, hex, or octal, passed the policy. 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 or CI builds; the same check is reused on redirects, so the gap also applies to each redirect hop. This issue is fixed in v0.163.1.

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.

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 0.60.0 to before 0.159.2, links and image links in the default markdown to HTML renderer are not properly escaped. Hugo users who trust their Markdown content or have custom render hooks for links and images are not affected. This vulnerability is fixed in 0.159.2.