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CVE-2026-6322— fast-uri vulnerable to host confusion via percent-encoded authority delimiters

Quick assessment

Affected
fast-uri fast-uri
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.

fast-uri是Fastify开源的一个无依赖的RFC 3986 URI解析与工具箱。 fast-uri 3.1.1及之前版本存在安全漏洞，该漏洞源于normalize()函数解码主机组件内百分比编码的权限分隔符并在序列化期间重新发射为原始分隔符，结合允许域、编码的at符号和不同域的主机被重新发射为原始用户信息分隔符，改变URI的权限到第二个域，可能导致应用程序被引导到不同的权限。

CVSS 7.5 · High EPSS 0.51% · P44

Possible ATT&CK Techniques 1 AI

T1564.004 · NTFS File Attributes

Affected Version Matrix 2

VendorProduct Version RangeStatus
fast-uri fast-uri < 3.1.2 affected
3.1.2 unaffected
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I. Basic Information for CVE-2026-6322

Vulnerability Information
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Vulnerability Title
fast-uri vulnerable to host confusion via percent-encoded authority delimiters
Source: CVE Program / CVE List V5
Vulnerability Description
fast-uri normalize() decoded percent-encoded authority delimiters inside the host component and then re-emitted them as raw delimiters during serialization. A host that combined an allowed domain, an encoded at-sign, and a different domain was re-emitted with the at-sign as a raw userinfo separator, changing the URI's authority to the second domain. Applications that normalize untrusted URLs before host allowlist checks, redirect validation, or outbound request routing can be steered to a different authority than the input appeared to specify. Versions <= 3.1.1 are affected. Update to 3.1.2 or later.
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
fast-uri 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
fast-uri是Fastify开源的一个无依赖的RFC 3986 URI解析与工具箱。 fast-uri 3.1.1及之前版本存在安全漏洞，该漏洞源于normalize()函数解码主机组件内百分比编码的权限分隔符并在序列化期间重新发射为原始分隔符，结合允许域、编码的at符号和不同域的主机被重新发射为原始用户信息分隔符，改变URI的权限到第二个域，可能导致应用程序被引导到不同的权限。
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

Vendor Product Affected Versions CPE Subscribe
fast-uri fast-uri 0 ~ 3.1.2 -

II. Public POCs for CVE-2026-6322

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III. Intelligence Information for CVE-2026-6322

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Vendor Advisories for CVE-2026-6322 (1)

IV. Related Vulnerabilities

Same product: fast-uri
Same vendor: fast-uri
Same weakness: CWE-436