What’s Vulnerable › Vulnerabilities
CVE-2026-28803: Open Forms possible to view submission details of other people than intended
- Severity: medium (CVSS 6.5 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: 2026-03-11 · updated 2026-06-17
- Weakness: CWE-284
Description
Open Forms allows users create and publish smart forms. Prior to 3.3.13 and 3.4.5, to be able to cosign, the cosigner receives an e-mail with instructions or a deep-link to start the cosign flow. The submission reference is communicated so that the user can retrieve the submission to be cosigned. Attackers can guess a code or modify the received code to look up arbitrary submissions, after logging in (with DigiD/eHerkenning/... depending on form configuration). This vulnerability is fixed in 3.3.13 and 3.4.5.
Affected products
- open-formulieren open-forms: before 3.3.13; from 3.4.0 before 3.4.5 — fixed in 3.3.13, 3.4.5
How to fix
Upgrade to a fixed version: open-formulieren open-forms 3.3.13, 3.4.5. Check the vendor advisory for mitigations.
References
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