Inefficient Regular Expression Complexity in shescape
Impact
This impacts users that use shescape to escape arguments:
- for the Unix shell Bash, or any not-officially-supported Unix shell;
- using the
escapeorescapeAllfunctions with theinterpolationoption set totrue.
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);Patches
This bug has been patched in v1.6.1 which you can upgrade to now. No further changes required.
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
For more information
- Comment on commit 552e8ea
- Open an issue at https://github.com/ericcornelissen/shescape/issues (New issue > Question > Get started)
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | shescape | >= 1.5.10, < 1.6.1 | 1.6.1 |
References
- https://github.com/ericcornelissen/shescape/security/advisories/GHSA-cr84-xvw4-qx3c
- https://nvd.nist.gov/vuln/detail/CVE-2022-25918
- https://github.com/ericcornelissen/shescape/commit/552e8eab56861720b1d4e5474fb65741643358f9
- https://github.com/ericcornelissen/shescape
- https://github.com/ericcornelissen/shescape/blob/main/src/unix.js%23L52
- https://github.com/ericcornelissen/shescape/releases/tag/v1.6.1
- https://security.snyk.io/vuln/SNYK-JS-SHESCAPE-3061108
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-1333- Platform
- npm
- Package
shescape- Disclosed
- 25.10.2022
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-cr84-xvw4-qx3c - CC BY 4.0
Vulnerability history: shescape
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 13
- First → latest
- 03.2021 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 5
- Medium 4
- Low 2
Disclosures per year
- 2021: 1
- 2022: 4
- 2023: 2
- 2024: 0
- 2025: 1
- 2026: 5
-
Inefficient Regular Expression Complexity in shescape this entry
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