6.5

CVE-2026-8683: mattermost

CVSS: 6.5v3.1MediumAnalyzed
Published 15-06-2026Last modified 15-06-2026
Open JSON

Vulnerability summary

CVE-2026-8683 is a medium (CVSS 6.5) vulnerability in mattermost. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 27.8% 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
0.36%
0%100%
Low · +0.16 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 15-06-2026
    PublishedVulnerability first disclosed.
  2. 15-06-2026
    Last modifiedVulnerability information updated.

Description

Mattermost Desktop App versions <=6.1 5.5.13.0 fail to account for attempting to open extremely long URLs in the Mattermost Desktop App which allows a malicious server owner to crash the application via including a script to call window.open on a very large URL. Mattermost Advisory ID: MMSA-2026-00652

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.36%

Chance of exploitation in the next 30 days

Percentile

28%

Versus all other CVEs

30-day change

+0.16 pp

From 0.20% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.36%

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