CVE-2025-47279 is a low-severity (CVSS 3.1) CWE-401 vulnerability in undici. A fix is available for undici — see the affected versions and patch details below.
undici Denial of Service attack via bad certificate data
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-47279.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
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 | 5.29.0npm install undici@5.29.0 |
| 📦npm | undici | ≥ 6.0.0&&< 6.21.2 | 6.21.2npm install undici@6.21.2 |
| 📦npm | undici | ≥ 7.0.0&&< 7.5.0 | 7.5.0npm install undici@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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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.
Frequently Asked Questions
Is CVE-2025-47279 in your dependencies?
Find it across npm, including transitive dependencies.