reflex up to 0.8.14 Environment Variable /auth-codespace redirect_to

Summaryinfo

A vulnerability, which was classified as problematic, was found in reflex up to 0.8.14. The affected element is an unknown function of the file /auth-codespace of the component Environment Variable Handler. Executing a manipulation of the argument redirect_to can lead to redirect. This vulnerability appears as CVE-2025-62379. The attack may be performed from remote. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in reflex up to 0.8.14. This vulnerability affects some unknown functionality of the file /auth-codespace of the component Environment Variable Handler. The manipulation of the argument redirect_to with an unknown input leads to a redirect vulnerability. The CWE definition for the vulnerability is CWE-601. A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. As an impact it is known to affect integrity. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2025-62379 since 10/10/2025. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1204.001.

Upgrading to version 0.8.15 eliminates this vulnerability. Applying the patch ade12549f3c0ddab3d7382c581bc04a3c1f989ec is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Name

• reflex

Version

• 0.8.0
• 0.8.1
• 0.8.2
• 0.8.3
• 0.8.4
• 0.8.5
• 0.8.6
• 0.8.7
• 0.8.8
• 0.8.9
• 0.8.10
• 0.8.11
• 0.8.12
• 0.8.13
• 0.8.14

License

• open-source

CPE 2.3info

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CPE 2.2info

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