Path traversal in fast-uri - CVE-2026-6321
Published: July 22, 2026
Vulnerability identifier: #VU139082
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-2026-6321
CWE-ID: CWE-22
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 path-based policy checks.
The vulnerability exists due to path traversal in the normalize() and equal() functions when processing percent-encoded path separators and dot segments in attacker-controlled URLs. A remote attacker can supply a specially crafted URL to bypass path-based policy checks.
Applications that normalize or compare attacker-controlled URLs to enforce path-based policy are affected.
How to mitigate CVE-2026-6321
Install security update from vendor's website.