Vulnerability-Lookup

GHSA-W4HW-QCX7-56PR

Vulnerability from github – Published: 2026-07-24 22:34 – Updated: 2026-07-24 22:34

Summary

Shescape: Shell injection via unescaped parentheses on Windows with CMD

Details

Impact

This impacts users of Shescape on Windows that explicitly configure shell to CMD, or true with the default shell being CMD, using the escape and escapeAll APIs.

An attacker may be able to achieve shell injection depending on the original command.

import * as cp from "node:child_process";
import { Shescape } from "shescape";

// 1. Prerequisites
const options = {
    shell: "cmd.exe",
    // Or
    shell: true, // Only if the default shell is CMD
};

// 2. Payload
const payload = "x) else if a==a (echo y";

// 3. Usage
const shescape = new Shescape(options);
let escapedPayload;

escapedPayload = shescape.escape(payload);
// Or
escapedPayload = shescape.escapeAll([payload]);

// And (example)
const result = cp.execSync(`if defined FALSY (echo ${escapedPayload})`, options);

// 4. Impact
console.log(result.toString());
// Outputs "y" instead of ""

Patches

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 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.

Workarounds

Alternatively, users of Shescape can remove all instances of ( and ) from untrusted inputs.

For more information

Comment on Pull Request [#2651] for v2 and [#2649] for v3
Comment on commit [b4b34c3] for v2 and [43d70b5] for v3
Open an issue at https://github.com/ericcornelissen/shescape/issues (New issue > Question)

Severity

9.2 (Critical)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "shescape"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.14"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "shescape"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-150",
      "CWE-78"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-24T22:34:23Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Impact\n\nThis impacts users of Shescape on Windows that explicitly configure `shell` to CMD, or `true` with the default shell being CMD, using the `escape` and `escapeAll` APIs.\n\nAn attacker may be able to achieve shell injection depending on the original command.\n\n```javascript\nimport * as cp from \"node:child_process\";\nimport { Shescape } from \"shescape\";\n\n// 1. Prerequisites\nconst options = {\n    shell: \"cmd.exe\",\n    // Or\n    shell: true, // Only if the default shell is CMD\n};\n\n// 2. Payload\nconst payload = \"x) else if a==a (echo y\";\n\n// 3. Usage\nconst shescape = new Shescape(options);\nlet escapedPayload;\n\nescapedPayload = shescape.escape(payload);\n// Or\nescapedPayload = shescape.escapeAll([payload]);\n\n// And (example)\nconst result = cp.execSync(`if defined FALSY (echo ${escapedPayload})`, options);\n\n// 4. Impact\nconsole.log(result.toString());\n// Outputs \"y\" instead of \"\"\n\n```\n\n### Patches\n\nThis bug has been patched in [v2.1.14] and [v3.0.1] which you can upgrade to now.\n\nIf you are already using v3 of Shescape, no further changes are required. If you are using v2 of Shescape is recommended to upgrade as this version reaches end-of-life status on 2026-09-28, follow the [migration guide] to upgrade to v3.\n\nNo patches will be released for version of Shescape lower than v2.0.0.\n\n### Workarounds\n\nAlternatively, users of Shescape can remove all instances of `(` and `)` from untrusted inputs.\n\n### For more information\n\n- Comment on Pull Request [#2651] for v2 and [#2649] for v3\n- Comment on commit [b4b34c3] for v2 and [43d70b5] for v3\n- Open an issue at \u003chttps://github.com/ericcornelissen/shescape/issues\u003e (New issue \u003e Question)",
  "id": "GHSA-w4hw-qcx7-56pr",
  "modified": "2026-07-24T22:34:23Z",
  "published": "2026-07-24T22:34:23Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ericcornelissen/shescape/security/advisories/GHSA-w4hw-qcx7-56pr"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ericcornelissen/shescape/pull/2649"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ericcornelissen/shescape/pull/2651"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ericcornelissen/shescape/commit/43d70b59d09bbe5c3fd02ef08b3a123e977ed9de"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ericcornelissen/shescape/commit/b4b34c394e7f9da2775bb75381066b9a228c425f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ericcornelissen/shescape"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ericcornelissen/shescape/blob/dea8893a5877893d8d4923dbf253080e08899e6d/docs/migration.md"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ericcornelissen/shescape/releases/tag/v2.1.14"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ericcornelissen/shescape/releases/tag/v3.0.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Shescape: Shell injection via unescaped parentheses on Windows with CMD"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

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