Bug 2458596 (CVE-2026-33806) - CVE-2026-33806 fastify: Fastify: Schema validation bypass via malformed Content-Type header
Summary: CVE-2026-33806 fastify: Fastify: Schema validation bypass via malformed Conte...
Keywords:
Status: NEW
Alias: CVE-2026-33806
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-04-15 02:02 UTC by OSIDB Bzimport
Modified: 2026-04-15 20:08 UTC (History)
4 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-04-15 02:02:14 UTC 
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. The body is still parsed correctly but schema validation is skipped.

This is a regression introduced in fastify >= 5.3.2 by the fix for CVE-2025-32442

Patches:

Upgrade to fastify v5.8.5 or later.

Workarounds:

None. Upgrade to the patched version.
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