CVE-2023-35931 is a low-severity (CVSS 3.1) CWE-526 vulnerability in shescape. 1 public exploit reference exists, so weaponization risk is real. A fix is available for shescape — see the affected versions and patch details below.
Shescape potential environment variable exposure on Windows with CMD
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-35931.
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.
How urgent is this, really
CVE-2023-35931 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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
Impact
This impact users of Shescape:
- On Windows using the Windows Command Prompt (i.e.
cmd.exe), and - Using
quote/quoteAllorescape/escapeAllwith theinterpolationoption set totrue.
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
Patches
This bug has been patched in v1.7.1 which you can upgrade to now. No further changes are required.
Workarounds
Alternatively, users can remove all instances of % from user input, either before or after using Shescape.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | shescape | all versions | 1.7.1npm install shescape@1.7.1 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
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 1.7.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-35931 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 CVE-2023-35931 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-35931. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-35931 in your dependencies?
O3 Security finds CVE-2023-35931 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.