CVE-2026-111766
LowCVSS 3.7Summary
markdown-it is a Markdown parser. Prior to 14.3.3 and 15.0.3, when the html option or commonmark preset is enabled and constructs occur inside a paragraph, attacker-controlled Markdown containing repeated unterminated inline HTML comments, processing instructions, declarations, or CDATA sections reaches src/rules_inline/html_inline.ts. Its HTML_TAG_RE match searches the remaining suffix for the appropriate terminator; when no terminator is present, parsing advances to the next opener and repeats the match over overlapping input, causing quadratic processing and denial of service through event-loop blocking or an unresponsive browser main thread. HTML blocks and the default HTML-disabled configuration are not affected by these payloads. This issue is fixed in versions 14.3.3 and 15.0.3.
Risk Assessment
Denial of service may lead to unavailability of the application or browser, potentially disrupting organizational operations. However, it requires specific options to be enabled and delivery of malicious Markdown.
Recommendation
Update markdown-it to version 14.3.3 or 15.0.3 (or later). If possible, disable the html option or commonmark preset if not needed.
Other vulnerabilities in markdown-it
See all- CVE-2026-111759High
markdown-it is a Markdown parser. Prior to 14.3.2 and 15.0.2, when typographer: true is enabled, specially crafted Markdown can cause quadratic processing time in the smartquotes rule, leading to denial of service. The issue occurs with many opening double quotes followed by unmatched closing single quotes.
- CVE-2026-48988Medium
markdown-it is a Markdown parser that contains a denial-of-service vulnerability in versions 14.1.1 and below when typographer: true is enabled. The issue arises from quadratic processing in the smartquotes rule, leading to excessive CPU consumption when parsing quote-heavy markdown.
Original NVD description (English source)
markdown-it is a Markdown parser. Prior to 14.3.3 and 15.0.3, when the html option or commonmark preset is enabled and the constructs occur inside a paragraph, attacker-controlled Markdown containing repeated unterminated inline HTML comments, processing instructions, declarations, or CDATA sections reaches src/rules_inline/html_inline.ts. Its HTML_TAG_RE match searches the remaining suffix for the appropriate terminator; when no terminator is present, parsing advances to the next opener and repeats the match over overlapping input, causing quadratic processing and denial of service through event-loop blocking or an unresponsive browser main thread. HTML blocks and the default HTML-disabled configuration are not affected by these payloads. This issue is fixed in versions 14.3.3 and 15.0.3.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS