CVE-2026-109165: TDuck survey form through 6.0 Authorization Bypass via User-Controlled Form Key in POST /user/form/item/batch/create

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-12 · updated 2026-10-16
Weakness: CWE-639

Description

TDuck survey form through 6.0 contains a broken access control vulnerability that allows authenticated users to add fields to other users' forms via POST /user/form/item/batch/create. Attackers can submit an array whose first element references their own form and later elements reference a victim's formKey, injecting attacker-chosen fields onto the victim's public fill page.

Affected products

TDuckCloud tduck-survey-form: through 6.0

References

https://github.com/AnkesKasty/cve-request-poc/blob/a7b6d1423555812d8efa26c91c5d0683164b31e5/tduck/poc_form_item_batch_create_cross_form.py
https://github.com/TDuckCloud/tduck-survey-form/blob/43ffa9c993e38936fc4de7d8e5aee82bbaa19502/tduck-api/src/main/java/com/tduck/cloud/api/web/controller/UserFormController.java#L327-L336
https://www.vulncheck.com/advisories/tduck-survey-form-through-6.0-authorization-bypass-via-user-controlled-form-key-in-post-user-form-item-batch-create

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