---
id: CVE-2026-109167
title: >-
  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
summary: >-
  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 ano…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-639
vendor: TDuckCloud
product: tduck-survey-form
affected:
  - tduck-survey-form <= 6.0
published: '2026-10-12'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:18:44.867'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109167'
references:
  - url: >-
      https://github.com/AnkesKasty/cve-request-poc/blob/a7b6d1423555812d8efa26c91c5d0683164b31e5/tduck/poc_user_form_theme_save_id_confusion.py
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/TDuckCloud/tduck-survey-form/blob/43ffa9c993e38936fc4de7d8e5aee82bbaa19502/tduck-api/src/main/java/com/tduck/cloud/api/web/controller/UserFormController.java#L393-L405
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/tduck-survey-form-through-6.0-authorization-bypass-via-user-controlled-theme-id-in-post-user-form-theme-save
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.0019
epssPercentile: 0.08519
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-14T15:51:17.953926Z'
ingestedAt: '2026-10-12T14:50:34.110Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.