High 7.5Published Apr 14, 2026

CVE-2026-33806fastify vulnerable to Body Schema Validation Bypass via Leading Space in Content-Type Header

Updated under an hour ago (Oct 27, 2026, 6:50 PM ET)

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It affects fastify and 3 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for fastify

Exploited in the last 30 days

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.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weakness (CWE): CWE-1287, CWE-1289
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: openjs
NVD analysis: Modified
Record last updated: Jul 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

fastify fastify fastify:fastify (from the name)	from 5.3.2 before 5.8.5; 5.8.5 not affected	CNA record
Red Hat Red Hat Enterprise Linux AI (RHEL AI) 3 redhat:enterprise_linux_ai	3	CISA ADP
Red Hat Red Hat OpenShift AI (RHOAI) redhat:openshift_ai	Versions not stated	CISA ADP
Red Hat Red Hat OpenShift Dev Spaces redhat:openshift_devspaces	3	CISA ADP
fastify fastify fastify:fastify	from 5.3.2 before 5.8.5	NVD

References

References

https://github.com/fastify/fastify/security/advisories/GHSA-mg2h-6x62-wpwc	not-applicable
https://cna.openjsf.org/security-advisories.html	vendor-advisory
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

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.