CVE-2026-28736 MEDIUM

CVE-2026-28736: Focalboard IDOR in file content endpoint allows cross-user file access (unsupported product, no fix)

Vendor Mattermost
Product Focalboard
Weakness CWE-639 · IDOR
Published April 3, 2026
Last update April 3, 2026
View on NVD All CVEs

CVSS base score

4.3/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality Low
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

What the vulnerability does

01Description

** UNSUPPORTED WHEN ASSIGNED ** Focalboard version 8.0 fails to validate file ownership when serving uploaded files. This allows an authenticated attacker who knows a victim's fileID to read the content of the file. NOTE: Focalboard as a standalone product is not maintained and no fix will be issued.

Key dates

02Disclosure timeline

April 3, 2026 CVE published
April 3, 2026 Record updated