{"id":"CVE-2026-59928","state":"PUBLISHED","title":"Mistune block_parser: quadratic-time parsing on long lists of repeated reference-link definitions","description":"Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links environment dictionary handling, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.","publishedAt":"2026-07-08T16:23:21.000Z","updatedAt":"2026-07-08T19:40:43.968Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["lepture mistune"],"affected":[{"vendor":"lepture","product":"mistune","versions":[{"version":"< 3.3.0","status":"affected"}]}],"references":["https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q","https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69","https://github.com/lepture/mistune/releases/tag/v3.3.0"],"weaknesses":["CWE-407","CWE-1333"],"ingestedAt":"2026-10-29T20:12:32.778Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/59xxx/CVE-2026-59928.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-59928","state":"PUBLISHED","datePublished":"2026-07-08T16:23:21.000Z","dateUpdated":"2026-07-08T19:40:43.968Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-07T18:20:06.126Z"},"containers":{"cna":{"title":"Mistune block_parser: quadratic-time parsing on long lists of repeated reference-link definitions","descriptions":[{"lang":"en","value":"Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links environment dictionary handling, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0."}],"affected":[{"vendor":"lepture","product":"mistune","versions":[{"version":"< 3.3.0","status":"affected"}]}],"references":[{"url":"https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q","name":"https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69","name":"https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69","tags":["x_refsource_MISC"]},{"url":"https://github.com/lepture/mistune/releases/tag/v3.3.0","name":"https://github.com/lepture/mistune/releases/tag/v3.3.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-407","lang":"en","description":"CWE-407: Inefficient Algorithmic Complexity","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-1333","lang":"en","description":"CWE-1333: Inefficient Regular Expression Complexity","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-08T16:23:21.000Z"},"source":{"advisory":"GHSA-ffq3-xpv3-j92q","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-08T17:46:13.539153Z","id":"CVE-2026-59928","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-08T19:40:43.968Z"}}]}}}