CVE-2026-4915: Improper Check for Unusual or Exceptional Conditions

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service server process termination via a crafted webhook...

Mattermost security vulnerabilities

Mattermost is an open source collaboration platform from Mattermost, Inc. in the United States. A security vulnerability in Mattermost versions 11.6.0 and prior to 11.6.x, 11.5.3 and prior to 11.5.x, 11.4.4 and prior to 11.4.x, and 10.11.14 and prior to 10.11.x, which stems from a failure to filt...