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TI-2026-22997 Aliases CVE-2026-28803

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

Priority LOW 28CWE-284Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-284.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00233 14th percentileScored 2026-11-07
Fix Fixed open-forms (open-formulieren): 3.4.5, 3.3.13

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
open-formulierenopen-forms3.4.0-alpha.0 to before 3.4.5; before 3.3.133.4.5, 3.3.13Patch availableCNA
  • open-forms Vendoropen-formulieren Affected 3.4.0-alpha.0 to before 3.4.5; before 3.3.13 Fixed in 3.4.5, 3.3.13 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:maykinmedia:open_forms:*:*:*:*:*:*:*:*before 3.3.13; 3.4.0 to before 3.4.5Vulnerableopen-formulieren
  • cpe:2.3:a:maykinmedia:open_forms:*:*:*:*:*:*:*:* Versions before 3.3.13; 3.4.0 to before 3.4.5 Vulnerable ·open-formulieren

Remediation

  • Fix · CNA open-forms (open-formulieren) Fixed in 3.4.5, 3.3.13

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-28803

References

Advisory 1

  • TI-2024-16288 Open Forms potential multi-factor authentication bypass CVSS 3.1HIGH 7.7
  • TI-2022-13086 Insufficient content-type validation for uploaded files in open-forms CVSS 3.1HIGH 7.6
  • TI-2022-13085 Open Redirect in open-forms CVSS 3.1HIGH 7.1
  • TI-2025-39905 Open Forms prefill data in read-only components can be tampered CVSS 3.1MEDIUM 4.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences