Bug 2436560 (CVE-2026-25223)

Summary: CVE-2026-25223 Fastify: Fastify: Validation bypass due to malformed Content-Type header leading to integrity impact
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: bbrownin, jkoehler, lphiri, sdawley
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Fastify, a web framework for Node.js. A remote attacker can exploit a validation bypass vulnerability by appending a tab character followed by arbitrary content to the Content-Type header. This circumvents the request body validation schemas, allowing the server to process the body as the original content type without proper validation. This could lead to unexpected data processing and potential integrity impact.
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Description OSIDB Bzimport 2026-02-03 22:01:43 UTC
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.