Cross-site scripting in React Router - CVE-2026-33244
Published: June 19, 2026
Vulnerability identifier: #VU134923
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-33244
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 user to execute arbitrary script in the victim's browser.
The vulnerability exists due to cross-site scripting in prerendered redirect HTML generation when processing an untrusted HTTP Location header value. A remote user can supply a crafted redirect location to execute arbitrary script in the victim's browser.
Only applications using Framework Mode with pre-rendering enabled are vulnerable. User interaction is required to load the generated HTML file.
How to mitigate CVE-2026-33244
Install security update from vendor's website.