brace-expansion: Quadratic-time expansion of the `{a},b}` rewrite causes CPU denial of service — GHSA-Q2HR-2G5M-VWHR

Summary

### Summary Expanding `{a},b}`-shaped input takes time quadratic in the number of literal `}` characters, blocking the event loop. Bash preserves a quirk where a brace group followed by a comma set still expands (`{a},b}`). The parser implements this by rewriting the string and restarting the scan. Each pass absorbs exactly one `}` and re-scans from the beginning, so `n` trailing braces cost `n` full passes. ###…

Timeline

Published by source

2026-09-29

Risk context

• Reported severity or threat level: medium.
• Reported CVSS score: 5.3 out of 10.
• Reported EPSS value: 0.00301.
• Review exposure for the affected product or family: npm: brace-expansion.

Product

npm: brace-expansion

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

GHSA-Q2HR-2G5M-VWHR

Source

GitHub

Vendor

GitHub

Published by source

2026-09-29

Last source activity

2026-09-29

Additional identifiers

CVE-2026-102277

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.