CVE-2026-33806
Published:April 15, 2026
Updated:April 23, 2026
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.
Affected Packages
fastify (CDN_JS):
Affected version(s) >=5.0.0 <5.3.2Fix Suggestion:
Update to version 5.3.2fastify (CDN_JS):
Affected version(s) =4.29.0 <4.29.1Fix Suggestion:
Update to version 4.29.1fastify (NPM):
Affected version(s) >=5.3.2 <5.8.5Fix Suggestion:
Update to version 5.8.5fastify (NPM):
Affected version(s) >=5.0.0 <5.3.2Fix Suggestion:
Update to version 5.3.2fastify (NPM):
Affected version(s) =4.29.0 <4.29.1Fix Suggestion:
Update to version 4.29.1Related Resources (7)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Improper Validation of Specified Type of Input
EPSS
Base Score:
0.04
