Riskcovery

CVE-2026-33806

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

State
Published
Severity
7.5 High
Published
Apr 15, 2026
Updated
Jul 15, 2026
Reserved
Mar 23, 2026

Read the record on cve.org

Description

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.

Scores

CVSSScoreVectorSource
3.17.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Nopenjs
3.17.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Nredhat-SADP

Weaknesses

  • CWE-1287 Improper Validation of Specified Type of Input
  • CWE-1289 Improper Validation of Unsafe Equivalence in Input

Affected Products

ProductVersions
fastifyfastify
  • 5.3.2 to before 5.8.5Affected
  • 5.8.5Not affected

References

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