Fastify vulnerable to invalid content-type parsing, which could lead to validation bypass
Fastify is a fast and low overhead web framework, for Node.js. In versions 5.0.0 to 5.3.0 as well as version 4.29.0, applications that specify different validation strategies for different content types have a possibility to bypass validation by providing a _slightly altered_ content type such as with different casing or altered whitespacing before `;`. This was patched in v5.3.1, but the initial patch did not cover all problems. This has been fully patched in v5.3.2 and v4.29.1. A workaround involves not specifying individual content types in the schema.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-33806US | — | — | ||
Impact:
Fastify applications using schema.body.content for per-content-type body validation can have validation bypassed entirely by prepending a space to the Content-Type header.… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/32xxx/CVE-2025-32442.jsonADVISORY
- https://github.com/fastify/fastify/commit/436da4c06dfbbb8c24adee3a64de0c51e4f47418FIX
- https://github.com/fastify/fastify/commit/f3d2bcb3963cd570a582e5d39aab01a9ae692fe4FIX
- https://github.com/fastify/fastify/security/advisories/GHSA-mg2h-6x62-wpwcADVISORY
- https://hackerone.com/reports/3087928WEB
- https://nvd.nist.gov/vuln/detail/CVE-2025-32442ADVISORY
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