Contao: Path traversal in the images controller

[ Description ]Official description

Contao is an Open Source CMS. From version 5.0.0 until 5.3.50 and 5.7.12, ImagesController joins the user-controlled {path} parameter to the configured image target directory with Path::join() but does not use Path::isBasePath() to verify that the canonical path remains inside that directory. An unauthenticated request containing encoded parent-directory segments can therefore return files under the project directory through BinaryFileResponse when their names use an extension allowed by contao.image.valid_extensions. The route can also reveal whether arbitrary paths exist, and debug responses can disclose absolute filesystem paths, but paths below the upload directory were not shown to be readable. This issue is fixed in versions 5.3.50 and 5.7.12.

[ Fixes ]Fixes and patches

• contao/core-bundle 5.3.50Fixed version · GitHub Advisories · composer package contao/core-bundle: upgrade to 5.3.50 or later (affected >= 4.1.0, < 5.3.50)
• contao/core-bundle 5.7.12Fixed version · GitHub Advisories · composer package contao/core-bundle: upgrade to 5.7.12 or later (affected >= 5.4.0-RC1, < 5.7.12)

[ Packages ]Affected open-source packages

• contao/core-bundle composerAffected >= 4.1.0, < 5.3.50 · fixed in 5.3.50 · GHSA-mrvp-7wmx-5m4h
• contao/core-bundle composerAffected >= 5.4.0-RC1, < 5.7.12 · fixed in 5.7.12 · GHSA-mrvp-7wmx-5m4h

[ References ]References

• github.com/contao/contao/commit/867c055122fdf12220f973f862082037b695b9bd
• github.com/contao/contao/releases/tag/5.3.50
• github.com/contao/contao/releases/tag/5.7.12
• github.com/contao/contao/security/advisories/GHSA-mrvp-7wmx-5m4h