CVE-2026-33806

HIGH

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

Title source: cna
STIX 2.1

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.

References (5)

Core 5

Scores

CVSS v3 7.5
EPSS 0.0041
EPSS Percentile 33.5%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-1287 CWE-1289
Status published
Products (3)
fastify/fastify 5.3.2 - 5.8.5 (2 CPE variants)
fastify/fastify 5.8.5
npm/fastify 5.3.2 - 5.8.5npm
Published Apr 15, 2026
Tracked Since Apr 15, 2026