wger: Privilege escalation via trainer-login session chaining allows gym trainer to impersonate gym manager

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.1 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS

• CVE-2026-43978: 0.27% estimated exploitation activity in the next 30 days; percentile 18.46 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A gym trainer can escalate their session to any higher-privileged account (gym manager, general manager) by chaining two calls to the trainer-login endpoint. Once a trainer performs a legitimate switch into a low-privileged user, the session flag trainer.identity is set and this flag alone bypasses the permission check on all subsequent trainer-login calls, allowing the trainer to hop into any account including gym managers. Details In wger/core/views/user.py lines 169–178, the permission check uses an AND condition: After hop 1 (trainer → regular user), request.user is the regular user who has no gymtrainer permission, but session['trainer.identity'] is set. Line 169 evaluates: not False AND not False → the second operand short-circuits the check. Line 173 is never reached because the current user is no longer a trainer. The attacker can therefore call trainer-login again targeting a manager account and it succeeds. PoC Requirements: A running wger instance with at least one…

Published by the source

14 May 2026, 16:16 UTC

Last modified by the source

13 Jul 2026, 16:43 UTC

Source last checked

26 Oct 2026, 13:41 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9qpr-vc49-hqg2

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-9qpr-vc49-hqg2

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# Patch Next advisory brief: CVE-2026-43978

Advisory: wger: Privilege escalation via trainer-login session chaining allows gym trainer to impersonate gym manager
IDs: CVE-2026-43978, GHSA-9qpr-vc49-hqg2
Record: https://patchnext.com/advisories/cve-2026-43978 (revision 2, source checked 26 Oct 2026, 13:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI wger: affected <= 2.5

## Suggested inspection (read-only)
- `python -m pip show wger`: prints the installed version. Run with the environment that serves production active.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on wger.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-9qpr-vc49-hqg2 (OSV record GHSA-9qpr-vc49-hqg2 lists affected ranges: PyPI wger >=0 <=2.5)
- Verified: https://github.com/advisories/GHSA-9qpr-vc49-hqg2 (GitHub-reviewed advisory GHSA-9qpr-vc49-hqg2 lists affected ranges: PyPI wger >=0 <=2.5)

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