CVE-2026-115349Mistune 3.0.0 before 3.3.0 Denial of Service via Nested Bracket Parsing

Description

Mistune from 3.0.0 before 3.3.0 contains an algorithmic complexity denial of service vulnerability in the parse_link_text function in src/mistune/helpers.py. Attackers can submit markdown with deeply nested square brackets triggering quadratic parsing time, exhausting server CPU with small crafted requests.

Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.

Affected products and versions

References and patches

• GitHub Security Advisory (GHSA-3q64-rw38-243v) vendor-advisory
• VulnCheck Advisory: Mistune 3.0.0 before 3.3.0 Denial of Service via Nested Bracket Parsing third-party-advisory