Interpretation Conflict in fast-uri - CVE-2026-6322
Published: July 22, 2026
Vulnerability identifier: #VU139083
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-6322
CWE-ID: CWE-436
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: fastify.io
Affected software:
fast-uri
fast-uri
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass host-based security checks and route requests to an unintended authority.
The vulnerability exists due to interpretation conflict in the URI host component when processing percent-encoded authority delimiters. A remote attacker can supply a specially crafted URL to bypass host-based security checks and route requests to an unintended authority.
This issue can affect applications that normalize untrusted URLs before host allowlist checks, redirect validation, or outbound request routing.
How to mitigate CVE-2026-6322
Install security update from vendor's website.