CVE-2026-25223— Fastify's Content-Type header tab character allows body validation bypass
Quick assessment
Affected
fastify fastify
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Fastify是Fastify开源的一个 Web 框架。 Fastify 5.7.2之前版本存在安全漏洞，该漏洞源于请求正文验证模式可被完全绕过，可能导致攻击者绕过正文验证。
Possible ATT&CK Techniques 1 AI
T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-25223
Vulnerability Information
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Vulnerability Title
Fastify's Content-Type header tab character allows body validation bypass
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
解释冲突
Source: CVE Program / CVE List V5
Vulnerability Title
Fastify 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Fastify是Fastify开源的一个 Web 框架。 Fastify 5.7.2之前版本存在安全漏洞，该漏洞源于请求正文验证模式可被完全绕过，可能导致攻击者绕过正文验证。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-25223
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2026-25223 (1)
Vendor Advisories for CVE-2026-25223 (1)
Vendor Pages for CVE-2026-25223 (1)
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Validation-and-Serialization | Fastify x_refsource_MISC
IV. Related Vulnerabilities
Same product: fastify
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CVE-2026-92081
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CVE-2026-76169
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CVE-2026-84504
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Same vendor: fastify
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CVE-2026-92081
fastify vulnerable to Denial of Service via unhandled except -
CVE-2026-84428
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CVE-2026-84469
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CVE-2026-76169
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CVE-2026-84504
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Same weakness: CWE-436
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V. Comments for CVE-2026-25223
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