🛡️ CVE-2026-33806 — fastify
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.
How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity high, availability none.
Weakness class
CVE-2026-33806 is classified as CWE-1287: Improper Validation of Specified Type of Input. The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.
Affected software
CVE-2026-33806 is recorded against 1 package.
- fastify (from 5.3.2 up to 5.8.5)
Timeline and source
Published on 15 April 2026 and last revised on 15 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.
References
cna.openjsf.org
github.com
access.redhat.com
bugzilla.redhat.com
security.access.redhat.com
Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| fastify | 5.3.2 | 5.8.5 |
References
Similar Threats
- Unknown CLSA-2026-1786387037
- Unknown MAL-2026-12379
- Unknown CLSA-2026-1772669615
- Unknown CLSA-2026-1773620080
- Unknown CLSA-2026-1778201074
Site Security Check
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CVE-2026-33806 is rated CVSS 7.5 High. BotEraser scans your installation against known CVE records and tells you whether this vulnerability applies to the versions you actually run.
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