4.3

CVE-2026-28736: mattermost focalboard

CVSS: 4.3v3.1MediumAnalyzed
AliasesGHSA-vph7-r229-qxpfGO-2026-5670
Published 03-04-2026Last modified 03-04-2026
Open JSON

Vulnerability summary

CVE-2026-28736 is a medium (CVSS 4.3) vulnerability in mattermost focalboard. EPSS estimates a 0.27% chance of exploitation in the next 30 days, higher than 18% of scored vulnerabilities.

Overall risk
17/100
0100
Low · default modelHow is this calculated?
CVSS score
4.3/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.27%
0%100%
Low · +0.05 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
OPENSUSE-SU-2026:21483-1

Timeline

  1. 03-04-2026
    PublishedVulnerability first disclosed.
  2. 03-04-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.27%

Chance of exploitation in the next 30 days

Percentile

18%

Versus all other CVEs

30-day change

+0.05 pp

From 0.22% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.27%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Github.com/mattermost1 product
  • focalboard≤ 7.10.6 | All versions (No fix recorded)
Mattermost1 product

2 vendors · 2 products

References

3 links