fastify is a fast and low overhead web framework, for Node.js. Affected versions of fastify are subject to a denial of service via malicious use of the Content-Type header. An attacker can send an invalid Content-Type header that can cause the application to crash. This issue has been addressed in commit `fbb07e8d` and will be included in release version 4.8.1. Users are advised to upgrade. Users unable to upgrade may manually filter out http content with malicious Content-Type headers.

Affected: npm: fastify

### 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. ```js 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](https://hackerone.com/bugs?report_id=1715536&subject=fastify)

### For more information [Fastify security policy](https://github.com/fastify/fastify/security/policy)