Home/CVE/Impact: Fastify applications using schema.body.content for per-content-type body validation can have validation bypasse
CVE

CVE-2026-33806

Impact: Fastify applications using schema.body.content for per-content-type body validation can have validation bypasse

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.

HIGH · CVSS 7.5 EPSS 0.00107
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-1287Improper Validation of Specified Type of Input
▤

Affected Products & Versions

1
fastify>= 5.3.2 and < 5.8.5
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
npm fastify HIGH fixed in 5.8.5
▣

Scoring & Timeline

7.5
HIGH · CVSS v3.1 · ce714d77-add3-4f53-aff5-83d477b104bb
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD15 Apr 2026 · 04:17 AM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://cna.openjsf.org/security-advisories.htmlVendor Advisory
https://github.com/fastify/fastify/security/advisories/GHSA-mg2h-6x62-wpwcNot Applicable
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