CVE-2025-24033
HIGHCVE-2025-24033 is a high-severity (CVSS 7.5) CWE-770 vulnerability in @fastify/multipart. O3 Security confirms whether CVE-2025-24033 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
@fastify/multipart vulnerable to unlimited consumption of resources
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
@fastify/multipartnpmDescription
@fastify/multipart is a Fastify plugin for parsing the multipart content-type. Prior to versions 8.3.1 and 9.0.3, the saveRequestFiles function does not delete the uploaded temporary files when user cancels the request. The issue is fixed in versions 8.3.1 and 9.0.3. As a workaround, do not use saveRequestFiles.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @fastify/multipart | all versions | 8.3.1 |
| 📦npm | @fastify/multipart | ≥ 9.0.0&&< 9.0.3 | 9.0.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @fastify/multipart. 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 @fastify/multipart to 8.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-24033 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-2025-24033 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-2025-24033. 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-2025-24033 in your dependencies?
O3 detects CVE-2025-24033 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.