CVE-2026-33806

HIGH

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

Title source: cna

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 (2)

https://github.com/fastify/fastify/security/advisories/GHSA-mg2h-6x62-wpwc

https://cna.openjsf.org/security-advisories.html

Scores

CVSS v3 7.5

EPSS 0.0010

EPSS Percentile 26.9%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Details

CWE

CWE-1287

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