CVE-2026-33806
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.
Weakness
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 products
- fastify fastify
References
- https://cna.openjsf.org/security-advisories.html
- https://github.com/fastify/fastify/security/advisories/GHSA-mg2h-6x62-wpwc
- https://access.redhat.com/security/cve/CVE-2026-33806
- https://bugzilla.redhat.com/show_bug.cgi?id=2458596
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33806.json
Find the bug before an attacker does.
Sign in with GitHub and run your first audit in under a minute. The free plan needs no credit card.