CVE-2026-109167

5.3 mediumEPSS 0.2%

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.

CVSS 4.0: 5.3CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS 3.1: 4.3CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
EPSS: 0.2% chance of exploitation in the next 30 days; higher than 8% of CVEs (scores of 2026-10-25)
CWE: CWE-639
Published: 2026-10-12
Modified: 2026-10-16
Record from: the NVD, synced 2026-10-19

References

https://github.com/AnkesKasty/cve-request-poc/blob/a7b6d1423555812d8efa26c91c5d0683164b31e5/tduck/poc_user_form_theme_save_id_confusion.py
https://github.com/TDuckCloud/tduck-survey-form/blob/43ffa9c993e38936fc4de7d8e5aee82bbaa19502/tduck-api/src/main/java/com/tduck/cloud/api/web/controller/UserFormController.java#L393-L405
https://www.vulncheck.com/advisories/tduck-survey-form-through-6.0-authorization-bypass-via-user-controlled-theme-id-in-post-user-form-theme-save

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