Mattermost versions 9.9.x <= 9.9.0 and 9.5.x <= 9.5.6 fail to validate the source of sync messages and only allow the correct remote IDs, which allows a malicious remote to set arbitrary RemoteId values for synced users and therefore claim that a user was synced from another remote.
{ "nvd_published_at": "2024-08-01T15:15:13Z", "cwe_ids": [ "CWE-284", "CWE-346" ], "severity": "MODERATE", "github_reviewed": true, "github_reviewed_at": "2024-08-02T01:19:49Z" }