CVE-2026-48988
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk16th percentile - higher than 16% of all known CVEs
Summary
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.
Risk Assessment
Attackers can exploit this vulnerability to degrade or disrupt service availability, impacting production applications that enable this option for better typography.
Recommendation
It is recommended to upgrade to version 14.2.0 or disable the typographer option to minimize the risk of denial of service.
Other vulnerabilities in markdown-it
See all- CVE-2026-111758High
markdown-it versions 14.1.0 to before 14.3.3 and 15.0.0 to before 15.0.3 are O(n²) with default options when parsing a link reference definition whose label or title is never closed, leading to excessive resource consumption.
- CVE-2026-111766Low
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.
- 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.
Original NVD description (English source)
markdown-it is a Markdown parser. Versions 14.1.1 and below contain a denial-of-service vulnerability when typographer: true is enabled, due to quadratic (O(n^2)) processing in the smartquotes rule. The issue stems from repeatedly modifying strings with replaceAt(), which performs O(n) slicing and concatenation per quote character. This can cause excessive CPU consumption when parsing quote-heavy, user-supplied markdown and may let attackers degrade or disrupt service availability. Although typographer is disabled by default, many production apps enable it for smart typography, making the issue relevant. This issue has been fixed in version 14.2.0.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS