CVE-2026-109167 TDuck survey form through 6.0 Authorization Bypass via User-Controlled Theme ID in POST /user/form/theme/save
Authenticated attackers can overwrite other users' form themes by manipulating theme IDs, leading to unauthorized data modification.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-109167?
CVE-2026-109167 is a medium-severity missing authorization vulnerability in TDuckCloud tduck-survey-form, published on 12 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
TDuck survey form through 6.0 contains an insecure direct object reference vulnerability in the saveFormTheme handler that allows authenticated users to overwrite other users' form themes. Attackers whose form has no theme can submit another form's sequential theme id with their own formKey, replacing its colours and image URLs and removing the victim's theme.
Weakness: CWE-639
Which versions are affected by CVE-2026-109167?
How do I fix CVE-2026-109167?
No fix has been published for CVE-2026-109167 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-109167 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-109167 exists.
Sources
Also known as GHSA-w8cw-4mm2-mrw7.