Ruby on Rails: Path Traversal on Default Installed Rails Application (Asset Pipeline)

There is an information leak vulnerability in Sprockets. This vulnerability
has been assigned the CVE identifier CVE-2018-3760.

Versions Affected: 4.0.0.beta7 and lower, 3.7.1 and lower, 2.12.4 and lower.
Not affected: NONE
Fixed Versions: 4.0.0.beta8, 3.7.2, 2.12.5

Impact

Specially crafted requests can be used to access files that exists on
the filesystem that is outside an application’s root directory, when the Sprockets server is
used in production.

All users running an affected release should either upgrade or use one of the work arounds immediately.

Releases

The 4.0.0.beta8, 3.7.2 and 2.12.5 releases are available at the normal locations.

Workarounds

In Rails applications, work around this issue, set config.assets.compile = false and
config.public_file_server.enabled = true in an initializer and precompile the assets.

This work around will not be possible in all hosting environments and upgrading is advised.

Patches

To aid users who aren’t able to upgrade immediately we have provided patches for the three supported release series.
They are in git-am format and consist of a single changeset.

• 4-0-fix-path-traversal.patch - Patch for the 4.0.x release series
• 3-7-fix-path-traversal.patch - Patch for the 3.7.x release series
• 2-12-fix-path-traversal.patch - Patch for the 2.12.x release series

Credits

Thanks to Orange Tsai from DEVCORE for reporting this issue.