CVE-2026-86349 Mattermost Server Algorithmic DoS via Unbounded Markdown Block Nesting

Mattermost versions 11.9.x = 11.9.0, 11.8.x = 11.8.4, 11.7.x = 11.7.8, 10.11.x = 10.11.22 fail to limit the nesting depth in the server-side Markdown parser which allows an authenticated attacker to cause a denial of service CPU resource exhaustion via a crafted post containing deeply nested...