{"schema_version":"1","data":[{"id":5450,"advisory_id":"88466912-d30d-443c-8d85-dbc56cbccbe6","revision":1,"source_id":"core-cve","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-66046","source_published_at":"2026-08-18T14:10:05.176+00:00","published_at":"2026-10-24T22:08:08.52895+00:00","extraction_method":"structured","technologies":["core-cve","libexpat"],"cve_ids":["CVE-2026-66046"],"event_types":["advisory"],"payload":{"kind":"advisory","title":"Expat Denial of Service via storeAtts() Quadratic Complexity","summary":"Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options.","evidence":"cve:CVE-2026-66046","products":[{"name":{"value":"libexpat","evidence":"/containers/cna/affected/0/product"},"prerequisites":[],"fixed_versions":[],"affected_versions":[]}],"severity":"high","structured":{"id":"CVE-2026-66046","aliases":["CVE-2026-66046"],"metrics":[{"format":"CVSS","cvssV4_0":{"Safety":"NOT_DEFINED","version":"4.0","Recovery":"NOT_DEFINED","baseScore":8.7,"Automatable":"NOT_DEFINED","attackVector":"NETWORK","baseSeverity":"HIGH","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","exploitMaturity":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","userInteraction":"NONE","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","subIntegrityImpact":"NONE","vulnIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"},"scenarios":[{"lang":"en","value":"GENERAL"}]},{"format":"CVSS","cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.5,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"NONE"},"scenarios":[{"lang":"en","value":"GENERAL"}]}],"affected":[{"repo":"https://github.com/libexpat/libexpat","vendor":"libexpat project","product":"libexpat","versions":[{"status":"affected","version":"0","versionType":"semver","lessThanOrEqual":"2.8.3"}],"packageURL":"pkg:github/libexpat/libexpat","defaultStatus":"affected"}],"modified":"2026-10-01T15:20:15.522Z","provider":"cve","references":["https://github.com/libexpat/libexpat/pull/1321","https://www.vulncheck.com/advisories/expat-denial-of-service-via-storeatts-quadratic-complexity"],"provider_metadata":{"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-66046","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-08-20T13:48:24.577412Z"}}}],"providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-08-20T15:24:17.474Z"}}],"cna":{"orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","shortName":"VulnCheck","dateUpdated":"2026-10-01T15:20:15.522Z"}}},"related_cves":[{"value":"CVE-2026-66046","evidence":"/cveMetadata/cveId"}],"security_relevant":true,"severity_evidence":"/containers/cna/metrics"},"priority":{"reasons":["publisher_severity"],"severity":"high","linked_cves":[],"fix_available":false,"known_exploited":false,"publisher_severity":"high"},"context_update":false}],"next_after":5450,"next_before":5450}