Medium severity · published Oct 12, 2026
CVE-2026-109167
TDuck survey form through 6.0 Authorization Bypass via User-Controlled Theme ID in POST /user/form/theme/save
4.3
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 9% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
TD
tduck-survey-form · TDuckCloud
through 6.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-109167
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-109167
exploit
https://github.com/AnkesKasty/cve-request-poc/blob/a7b6d1423555812d8efa26c91c5d0683164b31e5/tduck/poc_user_form_theme_save_id_confusion.py
technical-description
https://github.com/TDuckCloud/tduck-survey-form/blob/43ffa9c993e38936fc4de7d8e5aee82bbaa19502/tduck-api/src/main/java/com/tduck/cloud/api/web/controller/UserFormController.java#L393-L405
third-party-advisory
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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7.1
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6.5
CVE-2026-92567
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5.4
CVE-2026-100303
TDuck survey form through 6.0 Missing Authorization in Form Theme Management Endpoints
5.3
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