CVE-2025-62379 Open Redirect in reflex-dev/reflex
Attackers can redirect users to malicious sites via the auth-codespace endpoint in Reflex when Codespaces environment variables are set.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2025-62379?
CVE-2025-62379 is a low-severity vulnerability in reflex-dev reflex, published on 15 Oct 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-601
Which versions are affected by CVE-2025-62379?
3 open source packages ship an affected version, including reflex.
| Package | Affected | Fixed in |
|---|---|---|
reflex PyPI | From 0.5.4 to 0.8.14 | None |
reflex PyPI | From 0.5.4 to 0.8.14 | None |
reflex PyPI | From 0.5.4 to 0.8.14 | None |
How do I fix CVE-2025-62379?
No fix has been published for CVE-2025-62379 yet. Limit exposure of the affected software until one is available.
Is CVE-2025-62379 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-62379 exists.
Sources
Also known as GHSA-rfh5-c9h5-q8jm, PYSEC-2026-1868.