CVE-2023-35931

Shescape potential environment variable exposure on Windows with CMD

Workarounds

Alternatively, users can remove all instances of % from user input, either before or after using Shescape.

References

• Shescape Pull request #982
• Shescape commit d0fce70
• Shescape Release v1.7.1

This impact users of Shescape:

1. On Windows using the Windows Command Prompt (i.e. cmd.exe), and
2. Using quote/quoteAll or escape/escapeAll with the interpolation option set to true.

An attacker may be able to get read-only access to environment variables. Example:

import * as cp from "node:child_process";
import * as shescape from "shescape";

// 1. Prerequisites
const options = {
    shell: "cmd.exe",
    // Or
    shell: undefined, // Only if the default shell is CMD

    // And
    interpolation: true, // Only applies to `escape` and `escapeAll` usage
}

// 2. Attack (one of many)
const payload = "%PATH%";

// 3. Usage
let escapedPayload;

escapedPayload = shescape.quote(payload, options);
// Or
escapedPayload = shescape.quoteAll([payload], options);
// Or
escapedPayload = shescape.escape(payload, options);
// Or
escapedPayload = shescape.escapeAll([payload], options);

// And (example)
const result = cp.execSync(`echo Hello ${escapedPayload}`, options);

// 4. Impact
console.log(result.toString());
// Outputs "Hello" followed by the contents of the PATH environment variable

CVE-2023-35931 has a CVSS score of 3.1 (Low). The vector is network-reachable, low 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 (1.7.1); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

This bug has been patched in v1.7.1 which you can upgrade to now. No further changes are required.

1. What is CVE-2023-35931? CVE-2023-35931 is a low-severity security vulnerability in shescape (npm), affecting versions < 1.7.1. It is fixed in 1.7.1.
2. How severe is CVE-2023-35931? CVE-2023-35931 has a CVSS score of 3.1 (Low). 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-2023-35931? shescape (npm) versions < 1.7.1 is affected.
4. Is there a fix for CVE-2023-35931? Yes. CVE-2023-35931 is fixed in 1.7.1. Upgrade to this version or later.
5. Is CVE-2023-35931 exploitable, and should I be worried? Whether CVE-2023-35931 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-2023-35931 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-2023-35931? Upgrade shescape to 1.7.1 or later.

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