Mistune has a ReDoS in LINK_TITLE_RE that allows denial of service via crafted Markdown input

SummaryA ReDoS Regular Expression Denial of Service vulnerability in LINKTITLERE allows an attacker who can supply Markdown for parsing to cause denial of service. A crafted 58-byte Markdown document blocks the parser for approximately 6 seconds measured on Apple M2, Python 3.14.3, with exponenti...

PT-2026-38088

Name of the Vulnerable Software and Affected Versions Mistune versions 3.0.0a1 through 3.2.0 Description A Regular Expression Denial of Service ReDoS exists in the LINK TITLE RE regular expression. An attacker can provide specially crafted Markdown for parsing that triggers catastrophic...