CVE-2021-42740

The shell-quote package before 1.7.3 for Node.js allows command injection. An attacker can inject unescaped shell metacharacters through a regex designed to support Windows drive letters. If the output of this package is passed to a real shell as a quoted argument to a command with exec(), an attacker can inject arbitrary commands. This is because the Windows drive letter regex character class is [A-z] instead of the correct [A-Za-z]. Several shell metacharacters exist in the space between capital letter Z and lower case letter a, such as the backtick character.

Untrusted input is inserted into a command that is later executed by the application, allowing the attacker to alter the intent of that command. Typical impact: arbitrary command execution in the application's environment.

CVE-2021-42740 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.7.3); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2021-42740? CVE-2021-42740 is a critical-severity command injection vulnerability in shell-quote (npm), affecting versions >= 1.6.3, <= 1.7.2. It is fixed in 1.7.3. Untrusted input is inserted into a command that is later executed by the application, allowing the attacker to alter the intent of that command.
2. How severe is CVE-2021-42740? CVE-2021-42740 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of shell-quote are affected by CVE-2021-42740? shell-quote (npm) versions >= 1.6.3, <= 1.7.2 is affected.
4. Is there a fix for CVE-2021-42740? Yes. CVE-2021-42740 is fixed in 1.7.3. Upgrade to this version or later.
5. Is CVE-2021-42740 exploitable, and should I be worried? Whether CVE-2021-42740 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-42740 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-42740? Upgrade shell-quote to 1.7.3 or later.