Fastify up to 5.7.1 Content-Type Header interpretation conflict

CVSS Meta Temp Score
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CTI Interest Score
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6.3$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic was found in Fastify up to 5.7.1. This vulnerability affects unknown code of the component Content-Type Header Handler. Such manipulation leads to interpretation conflict. This vulnerability is traded as CVE-2026-25223. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Fastify up to 5.7.1. It has been rated as problematic. Affected by this issue is an unknown function of the component Content-Type Header Handler. The manipulation with an unknown input leads to a interpretation conflict vulnerability. Using CWE to declare the problem leads to CWE-436. Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state. Impacted is integrity. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-25223 since 01/30/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available.

Upgrading to version 5.7.2 eliminates this vulnerability. Applying the patch 32d7b6add39ddf082d92579a58bea7018c5ac821 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-5157). Once again VulDB remains the best source for vulnerability data.

Productinfo

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Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (GitHub_M): 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Interpretation conflict
CWE: CWE-436
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Fastify 5.7.2
Patch: 32d7b6add39ddf082d92579a58bea7018c5ac821

Timelineinfo

01/30/2026 CVE reserved
02/04/2026 +5 days Advisory disclosed
02/04/2026 +0 days VulDB entry created
02/04/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-jx2c-rxcm-jvmq
Status: Confirmed

CVE: CVE-2026-25223 (🔒)
GCVE (CVE): GCVE-0-2026-25223
GCVE (VulDB): GCVE-100-344204
EUVD: 🔒

Entryinfo

Created: 02/04/2026 07:50
Updated: 02/04/2026 08:34
Changes: 02/04/2026 07:50 (65), 02/04/2026 08:34 (1)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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