CVE intelligence and bounded remediation

CVE-2021-21289 — Mechanize is an open-source ruby library that makes automated web interaction easy

High CVSS 8.3

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#save_as, Mechanize#download, Mechanize::Download#save, Mechanize::File#save, and Mechanize::FileResponse#read_body. This is fixed in version 2.7.7.

Severity
High
CVSS
8.3 (3.1)
Published
2021-02-02
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-78

Affected products

  • mechanize_project / mechanize
  • fedoraproject / fedora / 32
  • fedoraproject / fedora / 33
  • debian / debian_linux / 9.0

Matched remediation archetype

Command, code, expression, and template injection

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Check exposure

  • Trace untrusted values to process execution, interpreters, evaluators, template engines, dynamic imports, and administrative scripting features.
  • Determine whether the affected path is reachable across each trust boundary and which service account or host privilege it inherits.
  • Review configuration for optional execution features, unsafe compatibility modes, and shell invocation.

Remediate safely

  • Replace string-built commands or evaluated code with fixed operations and structured argument APIs that do not invoke a shell.
  • Use strict allowlists for operation identifiers and reject unexpected input before it reaches any interpreter.
  • Update the affected component and add inert regression tests covering metacharacters, encoding variants, and alternate request paths.

Authoritative sources

Complete CVE record and remediation plan

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