Cross-site scripting in fast-uri - CVE-2026-110306
Published: November 10, 2026
Vulnerability identifier: #VU164383
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N]
CVE-ID: CVE-2026-110306
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass scheme allowlists and execute scripts in a victim's browser through consuming applications.
The vulnerability exists due to improper decoding in fast-uri's scheme handling when unescape() decodes percent-encoded schemes before validation, turning otherwise inert input into executable URLs. A remote attacker can supply %6Aavascript:alert(1) or %u006Aavascript:alert(1) for normalization or resolution and subsequent rendering to trigger cross-site scripting upon victim interaction, or submit %68ttp://a/ to bypass equality-based allowlists through equal().
Affected software
fast-uri
ApplinX
ApplinX
How to mitigate CVE-2026-110306
Install security update from vendor's website.
fast-uri - addressed in versions 2.4.8, 3.1.9, 4.2.3