{"id":"DEBIAN-CVE-2026-66046","details":"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-\u003edefaultAtts 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.","modified":"2026-09-19T22:47:27.943639968Z","published":"2026-08-18T15:16:57Z","upstream":["CVE-2026-66046"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-66046"}],"affected":[{"package":{"name":"expat","ecosystem":"Debian:12","purl":"pkg:deb/debian/expat?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.5.0-1","2.5.0-1+deb12u1","2.5.0-1+deb12u2","2.5.0-1+deb12u3","2.5.0-2","2.6.0-1","2.6.1-1","2.6.1-2","2.6.2-1","2.6.2-2","2.6.3-1","2.6.3-2","2.6.4-1","2.7.0-1","2.7.1-1","2.7.1-2","2.7.2-1","2.7.3-1","2.7.3-2","2.7.4-1","2.7.5-1","2.8.0-1","2.8.0-2","2.8.1-1","2.8.2-1","2.8.2-1~deb13u1","2.8.3-1","2.8.3-1~deb13u1","2.8.4-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-66046.json"}},{"package":{"name":"expat","ecosystem":"Debian:13","purl":"pkg:deb/debian/expat?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.7.1-2","2.7.2-1","2.7.3-1","2.7.3-2","2.7.4-1","2.7.5-1","2.8.0-1","2.8.0-2","2.8.1-1","2.8.2-1","2.8.2-1~deb13u1","2.8.3-1","2.8.3-1~deb13u1","2.8.4-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-66046.json"}},{"package":{"name":"expat","ecosystem":"Debian:14","purl":"pkg:deb/debian/expat?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.8.4-1"}]}],"versions":["2.7.1-2","2.7.2-1","2.7.3-1","2.7.3-2","2.7.4-1","2.7.5-1","2.8.0-1","2.8.0-2","2.8.1-1","2.8.2-1","2.8.2-1~deb13u1","2.8.3-1","2.8.3-1~deb13u1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-66046.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"}]}