CVE-2026-8683 | BDVDB-2026-340221 Detail

MattermostMattermost

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

Impact#

Per CVSS v3.1: confidentiality impact none, integrity impact none, availability impact high. Attack vector: network.

Weaknesses#

CWE-770 Allocation of Resources Without Limits or Throttling

References#

https://mattermost.com/security-updates

Exploit#

No public exploit known

History#

Version 12026-06-15Record published in the CVE List.

Published

Published: 2026-06-15
Last modified: 2026-06-15

Vendor information

Vendor: Mattermost
Product: Mattermost

All Mattermost vulnerabilities

Score

6.5 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 9.8.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
<= 5.5.13
Fixed
Not stated
Vulnerable
Not stated
Fixed
6.2.0
Vulnerable
Not stated
Fixed
5.13.6.0

Scoring System

CVSS v4.0

Not available

CVSS v3.1

6.5 Medium

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Privileges Required	None
User Interaction	Required
Scope	Unchanged
Confidentiality	None
Integrity	None
Availability	High

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).