Executive brief
Fastify is a popular Node.js web framework used to build HTTP APIs and web services. A denial of service vulnerability allows attackers to crash or hang the server by sending requests with extremely large JSON payloads, disrupting service availability for legitimate users.
Technical details
Fastify versions before 0.38.0 are vulnerable to denial of service when processing HTTP requests with Content-Type set to application/json and exceptionally large payloads. The vulnerability stems from insufficient limits on request body size in the default JSON body parser, allowing attackers to exhaust server resources (memory and CPU) without authentication or user interaction. The attack vector is network-based and unauthenticated. Affected versions are all releases up to and including 0.37.0. The fix introduces a configurable jsonBodyLimit option to restrict the maximum size of JSON request bodies.
Affected products
- Fastify Fastify <0.38.0
Timeline
- 2018-06-07: disclosed: CVE-2018-3711 published on NVD
- 2018-01-08: patched: Fix merged in PR #627
- 2018-07-18: advisory: GHSA-mq6c-fh97-4gwv published