Server-Side Request Forgery (SSRF) in fast-uri - CVE-2026-75975
Published: August 25, 2026
Vulnerability identifier: #VU145066
CSH Severity: Medium
CVSS v4: 8.7 [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]
CVE-ID: CVE-2026-75975
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass host-policy checks and perform server-side request forgery.
The vulnerability exists due to improper input validation in the IPv6 literal normalization logic of fast-uri when normalizing untrusted URLs containing malformed bracketed IPv6 literals. A remote attacker can supply a specially crafted URL to bypass host-policy checks and perform server-side request forgery.
Malformed bracketed IPv6 literals with invalid trailing text are silently truncated to different valid IPv6 addresses, and parse().error is not set for these inputs.
Affected software
fast-uri
How to mitigate CVE-2026-75975
Install security update from vendor's website.
fast-uri - addressed in versions 2.4.5, 3.1.6, 4.1.3