CVE-2021-21289: Command Injection Vulnerability in Mechanize
Mechanize is an open-source ruby library that makes automated web interaction easy. In Mechanize from version 2.0.0 and before version 2.7.7 there is a command injection vulnerability. Affected versions of mechanize allow for OS commands to be injected using several classes' methods which implicitly use Ruby's Kernel.open method. Exploitation is possible only if untrusted input is used as a local filename and passed to any of these calls: Mechanize::CookieJar#load, Mechanize::CookieJar#saveas, Mechanize#download, Mechanize::Download#save, Mechanize::File#save, and Mechanize::FileResponse#readbody. This is fixed in version 2.7.7.
Other sources
This security advisory has been created for public disclosure of a Command Injection vulnerability that was responsibly reported by @kyoshidajp (Katsuhiko YOSHIDA).
Impact
Mechanize >= v2.0, < v2.7.7 allows for OS commands to be injected using several classes' methods which implicitly use Ruby's Kernel.open method. Exploitation is possible only if untrusted input is used as a local filename and passed to any of these calls:
- Mechanize::CookieJar#load: since v2.0 (see 208e3ed) - Mechanize::CookieJar#saveas: since v2.0 (see 5b776a4) - Mechanize#download: since v2.2 (see dc91667) - Mechanize::Download#save and #save! since v2.1 (see 98b2f51, bd62ff0) - Mechanize::File#save and #saveas: since v2.1 (see 2bf7519) - Mechanize::FileResponse#readbody: since v2.0 (see 01039f5)
Patches
These vulnerabilities are patched in Mechanize v2.7.7.
Workarounds
No workarounds are available. We recommend upgrading to v2.7.7 or later.
References
See https://docs.rubocop.org/rubocop/copssecurity.html#securityopen for background on why Kernel.open should not be used with untrusted input.
For more information
If you have any questions or comments about this advisory, please open an issue in sparklemotion/mechanize.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is CVE-2021-21289?
CVE-2021-21289 is a Command Injection vulnerability in the Mechanize Ruby library.
How does CVE-2021-21289 impact Mechanize?
CVE-2021-21289 allows for OS commands to be injected using certain methods in Mechanize.
What is the severity of CVE-2021-21289?
CVE-2021-21289 has a severity score of 8.3 out of 10.
Which versions of Mechanize are affected by CVE-2021-21289?
Mechanize versions >= 2.0 and < 2.7.7 are affected by CVE-2021-21289.
How can I fix CVE-2021-21289?
To fix CVE-2021-21289, update Mechanize to version 2.7.7 or later.