Bundler is a package for managing application dependencies in Ruby.
CVE-2021-43809
Bundler is a package for managing application dependencies in Ruby. In bundler versions before 2.2.33, when working with untrusted and apparently harmless Gemfile's, it is not expected that they lead to execution of external code, unless that's explicit in the ruby code inside the Gemfile itself. However, if the Gemfile includes gem entries that use the git option with invalid, but seemingly harmless, values with a leading dash, this can be false. To handle dependencies that come from a Git repository instead of a registry, Bundler uses various commands, such as git clone. These commands are being constructed using user input (e.g. the repository URL). When building the commands, Bundler versions before 2.2.33 correctly avoid Command Injection vulnerabilities by passing an array of arguments instead of a command string. However, there is the possibility that a user input starts with a dash (-) and is therefore treated as an optional argument instead of a positional one. This can lead to Code Execution because some of the commands have options that can be leveraged to run arbitrary executables. Since this value comes from the Gemfile file, it can contain any character, including a…
Assessment
- CVSS
- 6.7 (v3.1)
- Severity
- Medium
- EPSS
- 2.91% chance of exploitation in the next 30 days
- Known exploited
- Not listed in CISA KEV
- Exploit availability
- Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
- Published
- 8 December 2021
- Last updated
- 2 November 2026
- Assigner
- GitHub_M
CVSS vectorCVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
At the source
References
- https://github.com/rubygems/rubygems/security/advisories/GHSA-fj7f-vq84-fh43
- https://github.com/rubygems/rubygems/pull/5142
- https://github.com/rubygems/rubygems/commit/0fad1ccfe9dd7a3c5b82c1496df3c2b4842870d3
- https://github.com/rubygems/rubygems/commit/a4f2f8ac17e6ce81c689527a8b6f14381060d95f
- https://www.sonarsource.com/blog/securing-developer-tools-package-managers/
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