Command Injection Vulnerability in Mechanize (CVE-2021-21289)

Why this deserves its current priority

CVSS is 7.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps mechanize (rubygems). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
mechanizerubygems	>=2.0.0 <2.7.7	2.7.7

Recommended response

Check inventory. Check lockfiles and deployed manifests for mechanize.
Review the reported fix. Update mechanize to 2.7.7 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Feb 2, 2021
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Aug 7, 2026

Sources and claim methodology

Upstream source description

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#save_as`: 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 `#save_as`: since v2.1 (see 2bf7519) - `Mechanize::FileResponse#read_body`: 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/cops_security.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](https://github.com/sparklemotion/mechanize/issues/new).

Quoted source text, attributed separately from HOL analysis.