{"id":"CVE-2026-59928","summary":"Mistune block_parser: quadratic-time parsing on long lists of repeated reference-link definitions","details":"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.","aliases":["GHSA-ffq3-xpv3-j92q","PYSEC-2026-2216"],"modified":"2026-07-17T18:29:39.317443146Z","published":"2026-07-08T16:23:21Z","related":["SUSE-SU-2026:22655-1","openSUSE-SU-2026:21339-1"],"database_specific":{"cwe_ids":["CWE-1333","CWE-407"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59928.json","cna_assigner":"GitHub_M"},"references":[{"type":"WEB","url":"https://github.com/lepture/mistune/releases/tag/v3.3.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59928.json"},{"type":"ADVISORY","url":"https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59928"},{"type":"FIX","url":"https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/lepture/mistune","events":[{"introduced":"0"},{"fixed":"15c3b79325125272263d7d42492ec8f757447191"},{"fixed":"2b04d7ba341c16ac78fe82d3076bdd5c3de87c69"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"3.3.0"}],"source":["CPE_RANGE","REFERENCES"],"cpe":"cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*"}}],"versions":["v3.2.1","v3.2.0","v3.1.4","v3.1.3","v3.1.2","v3.1.1","v3.1.0","v3.0.1","v3.0.0","v3.0.0rc5","v3.0.0rc4","v3.0.0rc3","v3.0.0rc2","v3.0.0rc1","v3.0.0a3","v3.0.0a2","v3.0.0a1","v2.0.2","v2.0.1","v2.0.0","v2.0.0rc1","v2.0.0a6","v2.0.0a5","v2.0.0a4","v2.0.0a3","v2.0.0a2","v2.0.0a1","v0.8.4","v0.8.3","v0.8.2","v0.8.1","v0.8","v0.7.4","v0.7.3","v0.7.2","v0.7.1","v0.7","v0.6","v0.5.1","v0.5","v0.4.1","v0.4","v0.3.1","v0.3.0","v0.2.0","v0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-59928.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}