title:  Incorrect Authorization leads to Channel Member Count Leak
description: Mattermost fails to check the required permissions in the POST /api/v4/channels/stats/member_count API resulting in channel member counts being leaked to a user without permissions.
problem types: CWE-284: Improper Access Control
affected:
{
defaultStatus: unaffected
product: Mattermost
vendor: Mattermost
versions:
lessThanOrEqual: 8.1.7, status: affected, version: 0, versionType: semver
status: unaffected, version: 8.1.8
status: affected, version: 9.4.0
}
metrics:
cvssV3_1: [
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 3.1
baseSeverity: LOW
confidentialityImpact: LOW
integrityImpact: NONE
privilegesRequired: LOW
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
version: 3.1
]
format: CVSS
scenarios: GENERAL
solutions: Update Mattermost Server to versions 8.1.8, 9.4.0 or higher.