{"id":"CVE-2026-111766","state":"PUBLISHED","title":"markdown-it: Quadratic-time denial of service in inline HTML parsing with html enabled","description":"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.","publishedAt":"2026-10-19T19:47:46.488Z","updatedAt":"2026-10-26T17:37:11.818Z","severity":{"score":3.7,"label":"Low","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["markdown-it markdown-it"],"affected":[{"vendor":"markdown-it","product":"markdown-it","versions":[{"version":">= 15.0.0, < 15.0.3","status":"affected"},{"version":"< 14.3.3","status":"affected"}]}],"references":["https://github.com/markdown-it/markdown-it/security/advisories/GHSA-vfgh-jcmw-g37q","https://github.com/markdown-it/markdown-it/commit/928bc8c11ded60181c0e7fc5aa954eec582e8e79","https://github.com/markdown-it/markdown-it/commit/d99f48839d37af6fd8a2617516c43dab90755503","https://github.com/markdown-it/markdown-it/releases/tag/14.3.3","https://github.com/markdown-it/markdown-it/releases/tag/15.0.3"],"weaknesses":["CWE-400","CWE-407"],"ingestedAt":"2026-10-29T20:10:33.477Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/111xxx/CVE-2026-111766.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-111766","state":"PUBLISHED","datePublished":"2026-10-19T19:47:46.488Z","dateUpdated":"2026-10-26T17:37:11.818Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-10-16T17:52:09.082Z"},"containers":{"cna":{"title":"markdown-it: Quadratic-time denial of service in inline HTML parsing with html enabled","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"markdown-it","product":"markdown-it","versions":[{"version":">= 15.0.0, < 15.0.3","status":"affected"},{"version":"< 14.3.3","status":"affected"}]}],"references":[{"url":"https://github.com/markdown-it/markdown-it/security/advisories/GHSA-vfgh-jcmw-g37q","name":"https://github.com/markdown-it/markdown-it/security/advisories/GHSA-vfgh-jcmw-g37q","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/markdown-it/markdown-it/commit/928bc8c11ded60181c0e7fc5aa954eec582e8e79","name":"https://github.com/markdown-it/markdown-it/commit/928bc8c11ded60181c0e7fc5aa954eec582e8e79","tags":["x_refsource_MISC"]},{"url":"https://github.com/markdown-it/markdown-it/commit/d99f48839d37af6fd8a2617516c43dab90755503","name":"https://github.com/markdown-it/markdown-it/commit/d99f48839d37af6fd8a2617516c43dab90755503","tags":["x_refsource_MISC"]},{"url":"https://github.com/markdown-it/markdown-it/releases/tag/14.3.3","name":"https://github.com/markdown-it/markdown-it/releases/tag/14.3.3","tags":["x_refsource_MISC"]},{"url":"https://github.com/markdown-it/markdown-it/releases/tag/15.0.3","name":"https://github.com/markdown-it/markdown-it/releases/tag/15.0.3","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":3.7,"baseSeverity":"LOW","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","description":"CWE-400: Uncontrolled Resource Consumption","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-407","lang":"en","description":"CWE-407: Inefficient Algorithmic Complexity","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-19T19:47:46.488Z"},"source":{"advisory":"GHSA-vfgh-jcmw-g37q","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-111766","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-26T17:29:30.362422Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-26T17:37:11.818Z"}}]}}}