CVE-2025-47279 is a low-severity (CVSS 3.1) CWE-401 vulnerability in undici. O3 Security confirms whether CVE-2025-47279 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
undici Denial of Service attack via bad certificate data
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
undicinpmDescription
Undici is an HTTP/1.1 client for Node.js. Prior to versions 5.29.0, 6.21.2, and 7.5.0, applications that use undici to implement a webhook-like system are vulnerable. If the attacker set up a server with an invalid certificate, and they can force the application to call the webhook repeatedly, then they can cause a memory leak. This has been patched in versions 5.29.0, 6.21.2, and 7.5.0. As a workaound, avoid calling a webhook repeatedly if the webhook fails.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | undici | all versions | 5.29.0 |
| 📦npm | undici | ≥ 6.0.0&&< 6.21.2 | 6.21.2 |
| 📦npm | undici | ≥ 7.0.0&&< 7.5.0 | 7.5.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for undici. 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 undici to 5.29.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-47279 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-2025-47279 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-2025-47279. 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-2025-47279 in your dependencies?
O3 detects CVE-2025-47279 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.