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CVE-2026-33806

fastify vulnerable to Body Schema Validation Bypass via Leading Space in Content-Type Header

Published: Apr 15, 2026Updated: Jul 15, 2026 Sources: CVE List NVDCWE-1287
7.5HIGH
NVD MITRE
EPSS Score
0.4%
Top 66.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
Not available

Description

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-1287CWE-1289

Affected Products

fastify
oss-projectaka fastify-multipart, fastify/middie
fastifyLibrary
OSS Libraries / web-framework

Exploitability

Official Patch Available
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References

https://github.com/fastify/fastify/security/advisories/GHSA-mg2h-6x62-wpwc
github.com
https://cna.openjsf.org/security-advisories.html
cna.openjsf.org
https://access.redhat.com/security/cve/CVE-2026-33806
access.redhat.com
and 2 more references View all →

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