CVE-2026-111758: markdown-it Uncontrolled Resource Consumption

Vulnerability summary

CVE-2026-111758 is a high (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in markdown-it. EPSS estimates a 0.46% chance of exploitation in the next 30 days, higher than 38.4% of scored vulnerabilities.

Timeline

1. 20-10-2026
   PublishedVulnerability first disclosed.

Description

markdown-it is a Markdown parser. From versions 14.1.0 to before 14.3.3, and 15.0.0 to before 15.0.3, a link reference definition whose label or title is never closed is O(n²) with default options. Continuation lines are pulled lazily with str += lineContent in src/rules_block/reference.ts, and the subsequent charCodeAt and slice calls flatten the V8 cons-string, copying everything collected so far; this runs before the rule decides the definition is invalid. No options are required to trigger it. This issue has been patched in versions 14.3.3 and 15.0.3.

• CWE-400Uncontrolled Resource ConsumptionThe product does not properly control the allocation and maintenance of a limited resource.
• CWE-407Inefficient Algorithmic ComplexityAn algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.