CVE-2026-86435

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 excessiv...

CVE-2026-86435 commonmark 1.5.0 before 2.8.4 Denial of Service via Footnote

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 excessiv...

league/commonmark: Denial of service via duplicate footnote definitions

Impact The Footnote extension records one backref per footnote reference and then appends the entire backref list for every footnote definition block in the document, without ever de-duplicating or removing repeated definitions of the same label GatherFootnotesListener, populated by...