CVE-2025-62379 json
Open Redirect in reflex-dev/reflex
published last yr. modified 21d ago also GHSA-rfh5-c9h5-q8jm , PYSEC-2026-1868 , EUVD-2025-34684
- cvss
- 3.1
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 17%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
Is CVE-2025-62379 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- last yr.
Exploit prediction
0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 3.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N |
| GitHub | 3.1 | 3.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N |
| OSV | 3.1 | 3.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | reflex | >=0.5.4, <=0.8.14 |
no fix listed |
Affected products
- reflex-dev reflex
Classification
- Weakness
-
- CWE-601 URL Redirection to Untrusted Site
References
-
github.com
/reflex-dev/reflex/commit/ade12549f3c0ddab3d7382c581bc04a3c1f989ec
web
-
github.com
/reflex-dev/reflex/security/advisories/GHSA-rfh5-c9h5-q8jm
web
-
nvd.nist.gov
/vuln/detail/CVE-2025-62379
advisory
-
file.notion.so
/f/f/d105d145-04bc-45c5-b46c-ed880895e9de/a86c3e3b-f67f-45d1-8fa2-4aa0ba7d0068/poc.mp4?table=block&id=26955717
web
-
github.com
/reflex-dev/reflex
package
-
github.com
/reflex-dev/reflex/blob/51f9f2c2f52cac4d66c07683a12bc0237311b6be/reflex/utils/codespaces.py#L18-L46
web
-
pypi.org
/project/reflex
package
-
github.com
/advisories/GHSA-rfh5-c9h5-q8jm
advisory
Sources
- CVE List CVE-2025-62379
- GitHub Advisory GHSA-rfh5-c9h5-q8jm
- NVD CVE-2025-62379
- OSV PYSEC-2026-1868
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.