An issue was discovered in Flask-CORS (aka CORS Middleware for Flask) before 3.0.9. It allows ../ directory traversal to access private resources because resource matching does not ensure that pathnames are in a canonical format.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-25032
• corydolphin/flask-cors@67c4b2c
• https://github.com/corydolphin/flask-cors/releases/tag/3.0.9
• https://www.debian.org/security/2020/dsa-4775
• http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00028.html
• http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00032.html
• http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00039.html
• http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00048.html