3.8

CVE-2026-12284: mattermost Origin Validation Error

CVSS: 3.8v3.1LowAnalyzed
Published 17-09-2026Last modified 17-09-2026
Open JSON

Vulnerability summary

CVE-2026-12284 is a low (CVSS 3.8) Origin Validation Error vulnerability in mattermost. EPSS estimates a 0.13% chance of exploitation in the next 30 days, higher than 2.4% of scored vulnerabilities.

Overall risk
15/100
0100
Low · default modelHow is this calculated?
CVSS score
3.8/10
010
Low · v3.1 (CVE.org)
EPSS score
0.13%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 17-09-2026
    PublishedVulnerability first disclosed.
  2. 17-09-2026
    Last modifiedVulnerability information updated.

Description

Mattermost Desktop App versions <=6.2 6.2.2.0 fails to validate the IPC sender in the leaveCall handler which allows a malicious or compromised Mattermost server (or a user with script access to a connected server view) to disconnect an active call belonging to a different connected server via the desktopAPI.leaveCall IPC message. Mattermost Advisory ID: MMSA-2026-00699

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.13%

Chance of exploitation in the next 30 days

Percentile

2%

Versus all other CVEs

30-day change

0.00 pp

From 0.13% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.13%

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

Mattermost2 products

1 vendor · 2 products

References

1 links