What is CVE-2026-33806?

CVE-2026-33806 is a high-severity vulnerability in Fastify, classified under CWE-1287. CVSS score: 7.5/10. Published 2026-04-15.

How severe is CVE-2026-33806?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Fastify

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 i…

EPSS: 0.001 (28.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

Affected products

Fastify — versions 5.3.2, 5.8.5

Weakness classification (CWE)

CWE-1287

References

github.com/fastify/fastify/security/advisories/GHSA-mg2h-6x62-wpwc
cna.openjsf.org/security-advisories.html

Frequently asked questions

What is CVE-2026-33806?: CVE-2026-33806 is a high-severity vulnerability in Fastify, classified under CWE-1287. CVSS score: 7.5/10. Published 2026-04-15.
How severe is CVE-2026-33806?: High severity. CVSS v3 base score is 7.5 out of 10.