6.5

CVE-2025-9076: mattermost Missing Authorization

CVSS: 6.5v3.1MediumAnalyzed
AliasesGHSA-3vcm-c42p-3hhfGO-2025-3950
Published 15-09-2025Last modified 15-09-2025
Open JSON

Vulnerability summary

CVE-2025-9076 is a medium (CVSS 6.5) Missing Authorization vulnerability in mattermost. EPSS estimates a 0.26% chance of exploitation in the next 30 days, higher than 16.6% of scored vulnerabilities.

Overall risk
26/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.26%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 3 · Related 3
OPENSUSE-SU-2025:15564-1OPENSUSE-SU-2026:21483-1SUSE-SU-2025:03289-1

Timeline

  1. 15-09-2025
    PublishedVulnerability first disclosed.
  2. 15-09-2025
    Last modifiedVulnerability information updated.

Description

Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive user information via unsanitized user objects. This vulnerability affects Mattermost Server instances with shared channels enabled.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.26%

Chance of exploitation in the next 30 days

Percentile

17%

Versus all other CVEs

30-day change

0.00 pp

From 0.26% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.26%

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/mattermost/mattermost-server2 products
  • v5All versions (No fix recorded)
  • v6All versions (No fix recorded)
Mattermost2 products
Github.com/mattermost1 product
  • mattermost-server≥ 10.10.0, < 10.10.2 | ≥ 10.10.0+incompatible, < 10.10.2+incompatible
Github.com/mattermost/mattermost/server1 product
  • v8< 8.0.0-20250729073403-517ae758cd02 | All versions (No fix recorded)

4 vendors · 6 products

References

4 links