Skip to content
Patch Next
Sign inAdd to your agent

← Actionable
Medium, CVSS 6.5amended

brace-expansion: Zero-step sequence causes process hang and memory exhaustion

CVE-2026-33750GHSA-f886-m6hf-6m8v

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (brace-expansion 5.0.5, 3.0.2, 2.0.3, 1.1.13), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

Add to your agent

Affected packages

  • npm brace-expansion

    Affected
    >= 4.0.0, < 5.0.5>= 3.0.0, < 3.0.2>= 2.0.0, < 2.0.3< 1.1.13
    Fixed in
    2.0.3, 3.0.2, 5.0.5, 1.1.13

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
EPSS
  • CVE-2026-33750: 0.45% estimated exploitation activity in the next 30 days; percentile 38.94 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact A brace pattern with a zero step value (e.g., {1..2..0}) causes the sequence generation loop to run indefinitely, making the process hang for seconds and allocate heaps of memory. The loop in question: https://github.com/juliangruber/brace-expansion/blob/daa71bcb4a30a2df9bcb7f7b8daaf2ab30e5794a/src/index.ts#L184 test() is one of https://github.com/juliangruber/brace-expansion/blob/daa71bcb4a30a2df9bcb7f7b8daaf2ab30e5794a/src/index.ts#L107-L113 The increment is computed as Math.abs(0) = 0, so the loop variable never advances. On a test machine, the process hangs for about 3.5 seconds and allocates roughly 1.9 GB of memory before throwing a RangeError. Setting max to any value has no effect because the limit is only checked at the output combination step, not during sequence generation. This affects any application that passes untrusted strings to expand(), or by error sets a step value of 0. That includes tools built on minimatch/glob that resolve patterns from CLI arguments or…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-f886-m6hf-6m8v

  2. Revision 1 · created ·

    Published from osv record GHSA-f886-m6hf-6m8v

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-33750

Advisory: brace-expansion: Zero-step sequence causes process hang and memory exhaustion
IDs: CVE-2026-33750, GHSA-f886-m6hf-6m8v
Record: https://patchnext.com/advisories/cve-2026-33750 (revision 2, source checked 26 Oct 2026, 12:47 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: brace-expansion 5.0.5, 3.0.2, 2.0.3, 1.1.13. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm brace-expansion: affected >= 4.0.0, < 5.0.5; >= 3.0.0, < 3.0.2; >= 2.0.0, < 2.0.3; < 1.1.13; fixed in 2.0.3, 3.0.2, 5.0.5, 1.1.13

## Suggested inspection (read-only)
- `npm ls brace-expansion --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on brace-expansion.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-f886-m6hf-6m8v (OSV record GHSA-f886-m6hf-6m8v lists affected ranges: npm brace-expansion >=4.0.0 =3.0.0 =2.0.0 =0 <1.1.13 (fixed))
- Verified: https://github.com/advisories/GHSA-f886-m6hf-6m8v (GitHub-reviewed advisory GHSA-f886-m6hf-6m8v lists affected ranges: npm brace-expansion >=4.0.0 =3.0.0 =2.0.0 =0 <1.1.13)

Commands are suggestions: review each one before running it.

Loading voting…