CVE-2022-39288 is a high-severity (CVSS 7.5) CWE-754 vulnerability in fastify. EPSS puts its 30-day exploitation probability at 59.2% (99th percentile). A fix is available for fastify — see the affected versions and patch details below.
Denial of service in Fastify via Content-Type header
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2022-39288.
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.
fastifynpmDescription
Impact
An attacker can send an invalid Content-Type header that can cause the application to crash, leading to a possible Denial of Service attack. Only the v4.x line is affected.
(This was updated: upon a close inspection, v3.x is not affected after all).
Patches
Yes, update to > v4.8.0.
Workarounds
You can reject the malicious content types before the body parser enters in action.
const badNames = Object.getOwnPropertyNames({}.__proto__)
fastify.addHook('onRequest', async (req, reply) => {
for (const badName of badNames) {
if (req.headers['content-type'].indexOf(badName) > -1) {
reply.code(415)
throw new Error('Content type not supported')
}
}
})
References
See the HackerOne report #1715536
For more information
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | fastify | ≥ 4.0.0&&< 4.8.1 | 4.8.1npm install fastify@4.8.1 |
Affected Products
fastifyfastifyDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fastify, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update fastify to 4.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-39288 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2022-39288 in your dependencies?
Find it across npm, including transitive dependencies.