CVE-2025-62379
- CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N
- Published: 2025-10-15T16:15:36.357
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.
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How to fix 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 […]
Affected Versions:
❌ Vulnerable: 0.5.4 - 0.8.14
✅ Safe: ≥ 0.8.15
Exploit Difficulty: HARD
⏱️ Time to exploit: > 4 hours
🛠️ Required skills: Advanced security expertise
💰 Public exploits: Rare or not public
How to Fix:
- Check if you're running the affected product
- Verify version (vulnerable: 0.5.4 - 0.8.14)
- Update to ≥ 0.8.15 or later
- If patching is not immediately possible: restrict network exposure, apply least-privilege access
- Test the fix in a staging environment first
- Review logs for signs of exploitation
- Monitor for IOCs (Indicators of Compromise)
- Enable automatic security updates
- Set up vulnerability monitoring
- Review and harden security configurations
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