CVE-2026-33806
fastify vulnerable to Body Schema Validation Bypass via Leading Space in Content-Type Header
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-1287 |
| Vendor | fastify |
| Product | fastify |
| Published | Apr 15, 2026 |
| Last Updated | Jul 15, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
Affected Versions
fastify / fastify
5.3.2 < 5.8.5
References
github.com: https://github.com/fastify/fastify/security/advisories/GHSA-mg2h-6x62-wpwc cna.openjsf.org: https://cna.openjsf.org/security-advisories.html access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-33806 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2458596 security.access.redhat.com: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33806.json
Credits
mcollina climba03003 jsumners UlisesGascon 🔍 Vyntral