CVE-2026-4286 - Playbooks Plugin fails to validate team transfers, allowing unauthorized removal of member access via playbook update

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MEDIUM

Playbooks Plugin fails to validate team transfers, allowing unauthorized removal of member access via playbook update

Published May 18, 2026

4.3

MEDIUM

CVSS 3.1

EPSS 0.23%

Description

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to check if {{team_id}} was being changed when updating playbooks, allowing users with only {{Manage Playbook Configurations}} permission to change a playbook's team, bypassing manage members restriction via PUT api. Mattermost Advisory ID: MMSA-2025-00552

Affected products

Vendor Mattermost Product Mattermost Default
unaffected
- Version
  10.11.0
  Status
  affected
  Constraints
  <=10.11.13
- Version
  11.5.0
  Status
  affected
  Constraints
  <=11.5.1
- Version
  10.11.14
  Status
  unaffected
  Constraints
  -
- Version
  11.5.2
  Status
  unaffected
  Constraints
  -
- Version
  11.6.0
  Status
  unaffected
  Constraints
  -

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Mattermost

unaffected

Version	Status	Constraints
10.11.0	affected	<=10.11.13
11.5.0	affected	<=11.5.1
10.11.14	unaffected	-
11.5.2	unaffected	-
11.6.0	unaffected	-

github.com/mattermost/mattermost-plugin-playbooks

Go

Introduced 0 Fixed 1.41.1-0.20260213020129-e1d6ec2c94e6
github.com/mattermost/mattermost-server

Go

Introduced 10.11.0+incompatible Fixed 10.11.14+incompatible
github.com/mattermost/mattermost-server

Go

Introduced 11.5.0+incompatible Fixed 11.5.2+incompatible
github.com/mattermost/mattermost-server/v5

Go

Introduced 0 Fixed not fixed
github.com/mattermost/mattermost-server/v6

Go

Introduced 0 Fixed not fixed
github.com/mattermost/mattermost/server/v8

Go

Introduced 0 Fixed not fixed

Ecosystem	Package	Introduced	Fixed
Go	github.com/mattermost/mattermost-plugin-playbooks	0	1.41.1-0.20260213020129-e1d6ec2c94e6
Go	github.com/mattermost/mattermost-server	10.11.0+incompatible	10.11.14+incompatible
Go	github.com/mattermost/mattermost-server	11.5.0+incompatible	11.5.2+incompatible
Go	github.com/mattermost/mattermost-server/v5	0	not fixed
Go	github.com/mattermost/mattermost-server/v6	0	not fixed
Go	github.com/mattermost/mattermost/server/v8	0	not fixed

Remediation

Vendor solution

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

Weaknesses (1)

CWE-863

Incorrect Authorization

References (5)

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-30750
Advisory
https://github.com/advisories/GHSA-gvg4-jhmr-6j23
Advisory
https://github.com/mattermost/mattermost-plugin-playbooks/commit/e1d6ec2c94e695fb74e0c0c11c0d45e028bb96f3
https://mattermost.com/security-updates
vendor-advisoryVendor Advisory
https://nvd.nist.gov/vuln/detail/CVE-2026-4286

Link	Providers	Tags
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-30750		Advisory
https://github.com/advisories/GHSA-gvg4-jhmr-6j23		Advisory
https://github.com/mattermost/mattermost-plugin-playbooks/commit/e1d6ec2c94e695fb74e0c0c11c0d45e028bb96f3
https://mattermost.com/security-updates		vendor-advisoryVendor Advisory
https://nvd.nist.gov/vuln/detail/CVE-2026-4286