A Directory Traversal issue was discovered in RubyGems 2.7.6 and later through 3.0.2. Before making new directories or touching files (which now include path-checking code for symlinks), it would delete the target destination. If that destination was hidden behind a symlink, a malicious gem could delete arbitrary files on the user's machine, presuming the attacker could guess at paths. Given how frequently gem is run as sudo, and how predictable paths are on modern systems (/tmp, /usr, etc.), this could likely lead to data loss or an unusable system.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
| Link | Tags |
|---|---|
| https://hackerone.com/reports/317321 | third party advisory exploit |
| https://blog.rubygems.org/2019/03/05/security-advisories-2019-03.html | vendor advisory |
| https://access.redhat.com/errata/RHSA-2019:1429 | vendor advisory |
| http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00036.html | vendor advisory |
| https://lists.debian.org/debian-lts-announce/2020/08/msg00027.html | mailing list |