Vulnerability · Published Oct 12, 2026 · Assigned by VulnCheck

CVE-2026-109167TDuck survey form through 6.0 Authorization Bypass via User-Controlled Theme ID in POST /user/form/theme/save

Medium 4.3

In plain English

A medium-severity authorization bypass via user-controlled key in tduck-survey-form from TDuckCloud. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities).

Severity (CVSS 3.1)4.3Medium

Exploit odds (30 days)0.2%top 91.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

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.

Affected products (as reported)

Vendor	Product	Versions
TDuckCloud	tduck-survey-form	0 – through 6.0

Weakness: CWE-639 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

References

Researcher Proof of Concept exploit
Vulnerable Code (6.0) technical-description
VulnCheck Advisory: TDuck survey form through 6.0 Authorization Bypass via User-Controlled Theme ID in POST /user/form/theme/save third-party-advisory