SB2026061977 - Multiple vulnerabilities in React Router

Description

This security bulletin contains information about 2 vulnerabilities.

1) Cross-site scripting (CVE-ID: CVE-2026-33244)

CWE-ID: CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSSv4: 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

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.

2) Cross-site scripting (CVE-ID: CVE-2026-33245)

CWE-ID: CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSSv4: 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

The vulnerability allows a remote attacker to execute arbitrary script in the victim's browser.

The vulnerability exists due to cross-site scripting in unstable RSC redirect handling when processing javascript: redirect targets from untrusted sources. A remote attacker can supply a crafted redirect target to execute arbitrary script in the victim's browser.

This only affects applications using the unstable RSC APIs.

Remediation

Install update from vendor's website.

References

• https://github.com/remix-run/react-router/security/advisories/GHSA-f22v-gfqf-p8f3
• https://github.com/remix-run/react-router/security/advisories/GHSA-8646-j5j9-6r62