High severityNVD Advisory· Published Feb 3, 2026· Updated Feb 4, 2026
Fastify's Content-Type header tab character allows body validation bypass
CVE-2026-25223
Description
Fastify is a fast and low overhead web framework, for Node.js. Prior to version 5.7.2, a validation bypass vulnerability exists in Fastify where request body validation schemas specified by Content-Type can be completely circumvented. By appending a tab character (\t) followed by arbitrary content to the Content-Type header, attackers can bypass body validation while the server still processes the body as the original content type. This issue has been patched in version 5.7.2.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
fastifynpm | < 5.7.2 | 5.7.2 |
Affected products
2Patches
Vulnerability mechanics
References
8- github.com/advisories/GHSA-jx2c-rxcm-jvmqghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-25223ghsaADVISORY
- fastify.dev/docs/latest/Reference/Validation-and-Serializationghsax_refsource_MISCWEB
- github.com/fastify/fastify/blob/759e9787b5669abf953068e42a17bffba7521348/lib/content-type-parser.jsghsax_refsource_MISCWEB
- github.com/fastify/fastify/blob/759e9787b5669abf953068e42a17bffba7521348/lib/validation.jsghsax_refsource_MISCWEB
- github.com/fastify/fastify/commit/32d7b6add39ddf082d92579a58bea7018c5ac821ghsax_refsource_MISCWEB
- github.com/fastify/fastify/security/advisories/GHSA-jx2c-rxcm-jvmqghsax_refsource_CONFIRMWEB
- hackerone.com/reports/3464114ghsax_refsource_MISCWEB
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