A vulnerability was found in Mattermost up to 10.11.14/11.4.4/11.5.3/11.6.0 . It has been classified as problematic . This vulnerability affects unknown code of the component Notification Message Handler . Performing a manipulation results in race condition. This vulnerability is identified as CVE-2026-4635 . The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is recommended.