CVE-2026-86435 [HIGH] – commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in t

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Footnote extension that fails to deduplicate footnote definitions. Attackers can craft documents with duplicate footnote definitions and references to create quadratic output expansion, consuming excessive memory and CPU to exhaust server resources.