6.5

CVE-2026-3471: mattermost

CVSS: 6.5v3.1MediumAnalyzed
Published 18-05-2026Last modified 18-05-2026
Open JSON

Vulnerability summary

CVE-2026-3471 is a medium (CVSS 6.5) vulnerability in mattermost. EPSS estimates a 0.33% chance of exploitation in the next 30 days, higher than 24.5% 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
0.33%
0%100%
Low · +0.14 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 18-05-2026
    PublishedVulnerability first disclosed.
  2. 18-05-2026
    Last modifiedVulnerability information updated.

Description

Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling {{window.open('javascript:alert()');}}. Mattermost Advisory ID: MMSA-2026-00618

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.33%

Chance of exploitation in the next 30 days

Percentile

25%

Versus all other CVEs

30-day change

+0.14 pp

From 0.18% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.33%

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