CVE-2025-62379

Description

Reflex is a library to build full-stack web apps in pure Python. In versions 0.5.4 through 0.8.14, the /auth-codespace endpoint automatically assigns the redirect_to query parameter value directly to client-side links without any validation and triggers automatic clicks when the page loads in a GitHub Codespaces environment. This allows attackers to redirect users to arbitrary external URLs. The vulnerable route is only registered when a Codespaces environment is detected, and the detection is controlled by environment variables. The same behavior can be activated in production if the GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN environment variable is set. The vulnerability occurs because the code assigns the redirect_to query parameter directly to a.href without any validation and immediately triggers a click (automatic navigation), allowing users to be sent to arbitrary external domains. The execution condition is based on the presence of a sessionStorage flag, meaning it triggers immediately on first visits or in incognito/private browsing windows, with no server-side origin/scheme whitelist or internal path enforcement defenses in place. This issue has been patched in version 0.8.15. As a workaround, users can ensure that GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN is not set in a production environment.

CVSS v3.1 Score

3.1

LOW

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N

Weakness Type (CWE)

CWE-601 CWE-601

References

Other References

https://github.com/reflex-dev/reflex/commit/ade12549f3c0ddab3d7382c581bc04a3c1f989ec https://github.com/reflex-dev/reflex/security/advisories/GHSA-rfh5-c9h5-q8jm

Frequently Asked Questions

What is CVE-2025-62379? +

Reflex is a library to build full-stack web apps in pure Python. In versions 0.5.4 through 0.8.14, the /auth-codespace endpoint automatically assigns the redirect_to query parameter value directly to client-side links without any validation and triggers automatic clicks when the page loads in a GitHub Codespaces environment. This allows attackers to redirect users to arbitrary external URLs. The vulnerable route is only registered when a Codespaces environment is detected, and the detection is controlled by environment variables. The same behavior can be activated in production if the GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN environment variable is set. The vulnerability occurs because the code assigns the redirect_to query parameter directly to a.href without any validation and immediately triggers a click (automatic navigation), allowing users to be sent to arbitrary external domains. The execution condition is based on the presence of a sessionStorage flag, meaning it triggers immediately on first visits or in incognito/private browsing windows, with no server-side origin/scheme whitelist or internal path enforcement defenses in place. This issue has been patched in version 0.8.15. As a workaround, users can ensure that GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN is not set in a production environment. It has a CVSS v3.1 base score of 3.1 (LOW).

How severe is CVE-2025-62379? +

CVE-2025-62379 has a CVSS v3.1 score of 3.1 out of 10, rated LOW. This is a low-severity vulnerability with limited impact.

How do I check if I'm vulnerable to CVE-2025-62379? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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