Vulnerability Report

CVE-2026-25223

Title: Validation bypass in Fastify via Content-Type header manipulation

Other

Proof Of Concept

No public PoC currently indexed for CVE-2026-25223.

CWE Category CWE-436

Published Date Feb 03, 2026

Modified Date Feb 10, 2026

Exploit Status Not Found

Score 7.5 CVSS v3.1

Exploit Probability (EPSS)

0.02%

Vulnerability Summary

CVE-2026-25223: Fastify is a fast and low overhead web framework, for Node.js. Prior to version 5.7.2, a validation bypass vulnerability exists in Fastify where request body validation schemas specified by Content-Type can be completely circumvented. By appending a tab character (\t) followed by arbitrary content to the Content-Type header, attackers can bypass body validation while the server still processes the body as the original content type. This issue has been patched in version 5.7.2.

Impacted Vendors

fastify 1

Reference Links

https://fastify.dev/docs/latest/Reference/Validation-and-Serialization https://github.com/fastify/fastify/blob/759e9787b5669abf953068e42a17bffba7521348/lib/content-type-parser.js#L125 https://github.com/fastify/fastify/blob/759e9787b5669abf953068e42a17bffba7521348/lib/validation.js#L272 https://github.com/fastify/fastify/commit/32d7b6add39ddf082d92579a58bea7018c5ac821 https://github.com/fastify/fastify/security/advisories/GHSA-jx2c-rxcm-jvmq https://hackerone.com/reports/3464114

CVSS v3.1

Source Entity [email protected]

Severity HIGH

7.5

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

UNCHANGED

RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-25223 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

February 10, 2026 MODIFIED

Vulnerability data updated via NVD.

February 10, 2026 MODIFIED

Vulnerability data updated via NVD.

February 04, 2026 MODIFIED

Vulnerability data updated via NVD.

February 03, 2026 MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK

Complexity LOW

Privileges N/A

Interaction NONE

CVSS Vector String


                                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected Stack

No specific products linked.