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Medium · 4.3 CVE-2026-28736 EUVD-2026-18653GHSA-vph7-r229-qxpfGO-2026-5670

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

Published Apr 3, 2026 · Updated Apr 3, 2026 · Assigned by Mattermost

Description

** 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.

Affected products

VendorProductAffectedFixed
Mattermost Focalboard ≤ 8.0 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 govulncheck-vulndb 0.0.20260723T184607-160000.1.1 openSUSE-SU-2026:21483-1

Affected packages

EcosystemPackageAffectedFixedRecord
Go github.com/mattermost/focalboard <= 7.10.6 — GHSA-vph7-r229-qxpf
Go github.com/mattermost/focalboard all versions — GO-2026-5670

Advisories 1

References