CVE-2022-25918

Inefficient Regular Expression Complexity in shescape

Workarounds

Alternatively, a maximum length can be enforced on input strings to shescape to reduce the impact of the vulnerability. It is not recommended to try and detect vulnerable input strings, as the logic for this may end up being vulnerable to ReDoS itself.

References

• Shescape commit 552e8ea
• Shescape Release v1.6.1

For more information

• Comment on commit 552e8ea
• Open an issue at https://github.com/ericcornelissen/shescape/issues (New issue > Question > Get started)

This impacts users that use shescape to escape arguments:

• for the Unix shell Bash, or any not-officially-supported Unix shell;
• using the escape or escapeAll functions with the interpolation option set to true.

An attacker can cause polynomial backtracking in terms of the input string length due to a Regular Expression in shescape that is vulnerable to Regular Expression Denial of Service (ReDoS). Example:

import * as shescape from "shescape";

/* 1. Prerequisites */
const options = {
  interpolation: true,
  // and
  shell: "/bin/bash",
  // or
  shell: "some-not-officially-supported-shell",
  // or
  shell: undefined, // Only if the system's default shell is bash or an unsupported shell.
};

/* 2. Attack */
let userInput = '{,'.repeat(150_000); // polynomial backtracking

/* 3. Usage */
shescape.escape(userInput, options);
// or
shescape.escapeAll([userInput], options);

A regular expression with worst-case exponential or polynomial matching time is applied to untrusted input, causing excessive CPU use. Typical impact: denial of service when input is crafted to trigger backtracking.

CVE-2022-25918 has a CVSS score of 7.5 (High). 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 (1.6.1); upgrading removes the vulnerable code path.

Kodem intelligence

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This bug has been patched in v1.6.1 which you can upgrade to now. No further changes required.

1. What is CVE-2022-25918? CVE-2022-25918 is a high-severity inefficient regular expression (ReDoS) vulnerability in shescape (npm), affecting versions >= 1.5.10, < 1.6.1. It is fixed in 1.6.1. A regular expression with worst-case exponential or polynomial matching time is applied to untrusted input, causing excessive CPU use.
2. How severe is CVE-2022-25918? CVE-2022-25918 has a CVSS score of 7.5 (High). 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 shescape are affected by CVE-2022-25918? shescape (npm) versions >= 1.5.10, < 1.6.1 is affected.
4. Is there a fix for CVE-2022-25918? Yes. CVE-2022-25918 is fixed in 1.6.1. Upgrade to this version or later.
5. Is CVE-2022-25918 exploitable, and should I be worried? Whether CVE-2022-25918 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-2022-25918 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-2022-25918? Upgrade shescape to 1.6.1 or later.

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