Cross-site scripting in React Router - CVE-2026-53667
Published: July 22, 2026
Vulnerability identifier: #VU139179
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Green
CVE-ID: CVE-2026-53667
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Remix
Affected software:
React Router
React Router
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary script in the victim's browser.
The vulnerability exists due to improper input validation in the unstable RSC error handling path when processing redirects from untrusted sources. A remote attacker can supply a crafted redirect target to execute arbitrary script in the victim's browser.
This issue only affects applications using the unstable RSC APIs, and user interaction is required.
How to mitigate CVE-2026-53667
Install security update from vendor's website.