PYSEC-2026-1868

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Import Source
https://github.com/pypa/advisory-database/blob/main/vulns/reflex/PYSEC-2026-1868.yaml
JSON Data
https://api.osv.dev/v1/vulns/PYSEC-2026-1868
Aliases
Published
2026-07-07T16:03:07Z
Modified
2026-07-07T17:47:00Z
Severity
  • 3.1 (Low) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N CVSS Calculator
Summary
reflex-dev/reflex has an Open Redirect vulnerability
Details

Mitigation

Make sure GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN is not set in a production environment. So the following is correct:

assert os.getenv("GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN") is None

Vulnerability Description

Vulnerability Overview

  • When the GET /auth-codespace page loads in a GitHub Codespaces environment, it automatically assigns the redirect_to query parameter value directly to client-side links without any validation and triggers automatic clicks. This allows attackers to redirect users to arbitrary external URLs.
  • The route is only registered when a Codespaces environment is detected, and the detection is controlled by environment variables. This means that the same behavior can be activated in production if the corresponding environment variable is set.

Vulnerable Code Analysis

https://github.com/reflex-dev/reflex/blob/51f9f2c2f52cac4d66c07683a12bc0237311b6be/reflex/utils/codespaces.py#L18-L46

  • This 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, resulting in an open redirect vulnerability.
  • The execution condition is simply 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.

PoC

PoC Description

image
  • Used the production configuration from docker-example (docker-example/production-compose).
  • Added a Codespaces detection environment variable to the app container in compose.yaml to forcibly expose the route.
  • GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN: dummy
  • The reverse proxy (Caddy) needs to be configured to forward /auth-codespace to the backend (required depending on the environment).

curl Example

https://localhost/auth-codespace?redirect_to=http://google.com

PoC MP4 https://file.notion.so/f/f/d105d145-04bc-45c5-b46c-ed880895e9de/a86c3e3b-f67f-45d1-8fa2-4aa0ba7d0068/poc.mp4?table=block&id=26955717-5d2e-805a-b53c-e25ee03f1d4b&spaceId=d105d145-04bc-45c5-b46c-ed880895e9de&expirationTimestamp=1760508000000&signature=ZPp8PVldfGOh0gB5tVElRV6GN789R-EG0oxZgkFjjLU&downloadName=poc.mp4

image image

Impact

Phishing/Social Engineering Attacks

Users can be exploited by immediately redirecting from a trusted domain to external malicious sites, taking advantage of user trust. This enables login page spoofing, credential harvesting, and redirection to malware distribution pages.

Authentication/Session Flow Disruption

When users with valid sessions/cookies from the same origin click the link, they are redirected to unintended external domains, which can bypass or disrupt authentication/authorization flows. When combined with redirect-based flows like OAuth/OIDC, this can escalate into security incidents.

References

Affected packages

PyPI / reflex

Package

Name
reflex
View open source insights on deps.dev
Purl
pkg:pypi/reflex

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0.5.4
Last Affected
0.8.14

Affected versions

0.*
0.5.4
0.5.5a1
0.5.5a2
0.5.5
0.5.6a1
0.5.6a2
0.5.6
0.5.7a1
0.5.7
0.5.8a1
0.5.8
0.5.9.dev1
0.5.9a1
0.5.9
0.5.10a1
0.5.10a2
0.5.10a3
0.5.10
0.5.10.post1
0.6.0a1
0.6.0a2
0.6.0a3
0.6.0a4
0.6.0
0.6.1a1
0.6.1a2
0.6.1
0.6.2a1
0.6.2a2
0.6.2
0.6.2.post1
0.6.3a1
0.6.3a2
0.6.3a3
0.6.3a4
0.6.3
0.6.3.post1
0.6.4a1
0.6.4a2
0.6.4a3
0.6.4
0.6.5a1
0.6.5a2
0.6.5a3
0.6.5
0.6.6a1
0.6.6a2
0.6.6a3
0.6.6
0.6.6.post1
0.6.6.post2
0.6.6.post3
0.6.7a1
0.6.7a2
0.6.7
0.6.8a1
0.6.8a2
0.6.8
0.6.8.post1
0.7.0a1
0.7.0a2
0.7.0a3
0.7.0a4
0.7.0a5
0.7.0
0.7.0.post1
0.7.1a1
0.7.1a2
0.7.1a3
0.7.1a4
0.7.1a5
0.7.1
0.7.1.post1
0.7.2.dev1
0.7.2a1
0.7.2a2
0.7.2
0.7.2.post1
0.7.3a1
0.7.3a2
0.7.3
0.7.3.post1
0.7.4a0
0.7.4a1
0.7.4a2
0.7.4a3
0.7.4
0.7.4.post1
0.7.5a1
0.7.5
0.7.5.post1
0.7.6a0
0.7.6a1
0.7.6
0.7.6.post1
0.7.7a1
0.7.7a2
0.7.7
0.7.7.post1
0.7.8a1
0.7.8
0.7.8.post1
0.7.9a1
0.7.9a2
0.7.9
0.7.9.post1
0.7.10a1
0.7.10
0.7.10.post1
0.7.11a1
0.7.11
0.7.12a1
0.7.12
0.7.13a1
0.7.13a2
0.7.13
0.7.14a1
0.7.14a2
0.7.14a3
0.7.14a4
0.7.14a5
0.7.14a6
0.7.14
0.8.0a1
0.8.0a2
0.8.0a3
0.8.0a4
0.8.0a5
0.8.0a6
0.8.0a7
0.8.0
0.8.0.post1
0.8.1a1
0.8.1a2
0.8.1
0.8.1.post1
0.8.2a1
0.8.2
0.8.3a1
0.8.3a2
0.8.3a3
0.8.3
0.8.4a1
0.8.4a2
0.8.4
0.8.5a1
0.8.5a2
0.8.5
0.8.6a0
0.8.6a1
0.8.6
0.8.7a1
0.8.7
0.8.8a1
0.8.8a2
0.8.8
0.8.9a1
0.8.9a2
0.8.9
0.8.10a1
0.8.10
0.8.11a1
0.8.11
0.8.12a1
0.8.12a2
0.8.12
0.8.13a1
0.8.13
0.8.14a1
0.8.14a2
0.8.14

Database specific

source 
"https://github.com/pypa/advisory-database/blob/main/vulns/reflex/PYSEC-2026-1868.yaml"