CVE-2026-86256

wger before 2.6 (affected versions <= 2.5.0) contains an open redirect vulnerability in the trainer_login view (wger/core/views/user.py). After a trainer enters impersonation mode, the view redirects to the user-supplied 'next' GET parameter via HttpResponseRedirect() without validating it with url_has_allowed_host_and_scheme(). An attacker who delivers a crafted link to an authenticated trainer can redirect the trainer's browser to an attacker-controlled domain, enabling phishing and leaking the wger URL structure (including the impersonated user's user_pk) via the Referer header.

• https://github.com/wger-project/wger/security/advisories/GHSA-vqv8-j3mj-wjxj
• https://www.vulncheck.com/advisories/wger-before-2.6-open-redirect-via-trainer-login-next-parameter