views/switch.py in django-grappelli (aka Django Grappelli) before 2.15.2 attempts to prevent external redirection with startswith("/") but this does not consider a protocol-relative URL (e.g., //example.com) attack.
"https://github.com/pypa/advisory-database/blob/main/vulns/django-grappelli/PYSEC-2023-211.yaml"