CVE-2026-33750
MEDIUMCVE-2026-33750 is a medium-severity (CVSS 6.5) Uncontrolled Resource Consumption vulnerability in brace-expansion. O3 Security confirms whether CVE-2026-33750 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
brace-expansion: Zero-step sequence causes process hang and memory exhaustion
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
brace-expansionnpmDescription
The brace-expansion library generates arbitrary strings containing a common prefix and suffix. Prior to versions 5.0.5, 3.0.2, 2.0.3, and 1.1.13, 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. Versions 5.0.5, 3.0.2, 2.0.3, and 1.1.13 fix the issue. As a workaround, sanitize strings passed to expand() to ensure a step value of 0 is not used.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | brace-expansion | ≥ 4.0.0&&< 5.0.5 | 5.0.5 |
| 📦npm | brace-expansion | ≥ 3.0.0&&< 3.0.2 | 3.0.2 |
| 📦npm | brace-expansion | ≥ 2.0.0&&< 2.0.3 | 2.0.3 |
| 📦npm | brace-expansion | all versions | 1.1.13 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for brace-expansion. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update brace-expansion to 5.0.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33750 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-33750 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-33750. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-33750 in your dependencies?
O3 detects CVE-2026-33750 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.