CVE-2026-4055 PUBLISHED

Insufficient permission validation on cross-team playbook run creation

Assigner: Mattermost
Reserved: 12.03.2026 Published: 21.05.2026 Updated: 21.05.2026

Mattermost versions 11.5.x <= 11.5.1 fail to validate team-level run_create permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request. Mattermost Advisory ID: MMSA-2026-00629

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CVSS Score: 4.3

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

CVSS 3.1

Product Status

Vendor	Mattermost
Product	Mattermost
Versions	Default: unaffected affected from 11.5.0 to 11.5.1 (incl.) Version 11.6.0 is unaffected Version 11.5.2 is unaffected Version 10.11.14 is unaffected Version 11.4.4 is unaffected

Solutions

Update Mattermost to versions 11.6.0, 11.5.2, 10.11.14, 11.4.4 or higher.

Credits

0x7oda7123 finder

References

MMSA-2026-00629

Problem Types

CWE-863: Incorrect Authorization CWE