Описание
Hugo: Symlink confinement bypass in resources.Get
Commit: f8b5fa09a6 — Fix prevention of direct symlink reads in resources.Get
Affected versions: v0.123.0 through v0.161.1. Earlier versions are not affected.
Fixed in: v0.162.0.
Severity: Medium. Requires the attacker to be able to place (or convince a site author to place) a symlink inside a mounted directory — for example, inside a locally-vendored theme under themes/. Themes mounted as Go modules from GitHub have symlinks stripped on download and are not affected. Multi-directory walks (e.g. content/asset walking) were not affected either; only direct lookups via resources.Get followed symlinks.
Description. Hugo's virtual filesystem is designed so that files under a mount cannot reach outside the mount tree. A regression introduced in v0.123.0 caused RootMappingFs.statRoot to call Stat (which follows symlinks) instead of Lstat, so a direct resources.Get "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.
Mitigation. v0.162.0 calls LstatIfPossible and rejects symlinked entries with os.ErrNotExist, matching the behaviour of pre-v0.123.0 releases and of the directory-walking code paths.
Пакеты
github.com/gohugoio/hugo
>= 0.123.0, < 0.162.0
0.162.0
Связанные уязвимости
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 0.123.0 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 0.123.0 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 0.123.0 to 0.161.1, a regression ...