CVE-2026-8683 PUBLISHED

Overly long URLs crash the Mattermost Desktop App

Assigner: Mattermost
Reserved: 15.05.2026 Published: 15.06.2026 Updated: 15.06.2026

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

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS Score: 6.5

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

CVSS 3.1

Product Status

Vendor	Mattermost
Product	Mattermost
Versions	Default: unaffected affected from 0 to 5.5.13 (incl.) Version 6.2.0 is unaffected Version 5.13.6.0 is unaffected

Solutions

Update Mattermost Desktop App to versions 6.2.0, 5.13.6.0 or higher.

Credits

game0v3r finder

References

MMSA-2026-00652

Problem Types

CWE-770: Allocation of Resources Without Limits or Throttling CWE