CVE-2026-28803

Open Forms possible to view submission details of other people than intended

State: Published
Severity: 6.5 Medium
Published: Mar 11, 2026
Updated: Mar 11, 2026
Reserved: Mar 3, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	6.5 Medium	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N	GitHub_M

Weaknesses

CWE-284 Improper Access Control

Affected Products

Product	Versions
open-formsopen-formulieren	>= 3.4.0-alpha.0, < 3.4.5Affected < 3.3.13Affected

References

https://github.com/open-formulieren/open-forms/security/advisories/GHSA-2g49-rfm6-5qj5

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