CVE-2026-28803
March 11, 2026
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 Packages
https://github.com/open-formulieren/open-forms.git (GITHUB):
Affected version(s) >=3.4.0-leiden.0 <3.4.5Fix Suggestion:
Update to version 3.4.5https://github.com/open-formulieren/open-forms.git (GITHUB):
Affected version(s) >=1.0.0-rc.0 <3.3.13Fix Suggestion:
Update to version 3.3.13Related Resources (1)
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Contact UsCVSS v4
Base Score:
7.1
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
NONE
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Weakness Type (CWE)
Improper Access Control
EPSS
Base Score:
0.03
