{"id":"CVE-2018-20843","title":"In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service a…","summary":"In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service a…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-611","CWE-611"],"vendor":"libexpat_project","product":"libexpat","affected":["libexpat < 2.2.7","ubuntu_linux = 12.04","ubuntu_linux = 14.04","ubuntu_linux = 16.04","ubuntu_linux = 18.04","ubuntu_linux = 18.10","ubuntu_linux = 19.04","debian_linux = 8.0","debian_linux = 9.0","fedora = 29","fedora = 30","leap = 15.0","leap = 15.1","hospitality_res_3700 >= 5.7, <= 5.7.6","http_server = 12.1.3.0","http_server = 12.2.1.4.0","outside_in_technology = 8.5.4","outside_in_technology = 8.5.5","nessus < 8.15.0"],"patched":["libexpat 2.2.7","nessus 8.15.0"],"published":"2019-06-24","updated":"2026-10-14","sourceUpdated":"2026-10-14T07:16:43.890","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2018-20843","references":[{"url":"http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00039.html","label":"cve@mitre.org"},{"url":"https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5226","label":"cve@mitre.org"},{"url":"https://github.com/libexpat/libexpat/blob/R_2_2_7/expat/Changes","label":"cve@mitre.org"},{"url":"https://github.com/libexpat/libexpat/issues/186","label":"cve@mitre.org"},{"url":"https://github.com/libexpat/libexpat/pull/262","label":"cve@mitre.org"},{"url":"https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6","label":"cve@mitre.org"},{"url":"https://lists.debian.org/debian-lts-announce/2019/06/msg00028.html","label":"cve@mitre.org"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CEJJSQSG3KSUQY4FPVHZ7ZTT7FORMFVD/","label":"cve@mitre.org"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IDAUGEB3TUP6NEKJDBUBZX7N5OAUOOOK/","label":"cve@mitre.org"},{"url":"https://seclists.org/bugtraq/2019/Jun/39","label":"cve@mitre.org"},{"url":"https://security.gentoo.org/glsa/201911-08","label":"cve@mitre.org"},{"url":"https://security.netapp.com/advisory/ntap-20190703-0001/","label":"cve@mitre.org"},{"url":"https://support.f5.com/csp/article/K51011533","label":"cve@mitre.org"},{"url":"https://usn.ubuntu.com/4040-1/","label":"cve@mitre.org"},{"url":"https://usn.ubuntu.com/4040-2/","label":"cve@mitre.org"},{"url":"https://www.debian.org/security/2019/dsa-4472","label":"cve@mitre.org"},{"url":"https://www.oracle.com/security-alerts/cpuApr2021.html","label":"cve@mitre.org"},{"url":"https://www.oracle.com/security-alerts/cpuapr2020.html","label":"cve@mitre.org"},{"url":"https://www.oracle.com/security-alerts/cpuoct2020.html","label":"cve@mitre.org"},{"url":"https://www.oracle.com/security-alerts/cpuoct2021.html","label":"cve@mitre.org"},{"url":"https://www.tenable.com/security/tns-2021-11","label":"cve@mitre.org"},{"url":"http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00039.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5226","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/libexpat/libexpat/blob/R_2_2_7/expat/Changes","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/libexpat/libexpat/issues/186","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/libexpat/libexpat/pull/262","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2019/06/msg00028.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CEJJSQSG3KSUQY4FPVHZ7ZTT7FORMFVD/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IDAUGEB3TUP6NEKJDBUBZX7N5OAUOOOK/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://seclists.org/bugtraq/2019/Jun/39","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.gentoo.org/glsa/201911-08","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20190703-0001/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://support.f5.com/csp/article/K51011533","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://usn.ubuntu.com/4040-1/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://usn.ubuntu.com/4040-2/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.debian.org/security/2019/dsa-4472","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com/security-alerts/cpuApr2021.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com/security-alerts/cpuapr2020.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com/security-alerts/cpuoct2020.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com/security-alerts/cpuoct2021.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.tenable.com/security/tns-2021-11","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-398330.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd"],"epss":0.07107,"epssPercentile":0.94116,"ingestedAt":"2026-10-14T07:21:04.815Z","slug":"CVE-2018-20843","body":"## Overview\n\nIn libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).\n\n## Affected\n\n- `libexpat < 2.2.7`\n- `ubuntu_linux = 12.04`\n- `ubuntu_linux = 14.04`\n- `ubuntu_linux = 16.04`\n- `ubuntu_linux = 18.04`\n- `ubuntu_linux = 18.10`\n- `ubuntu_linux = 19.04`\n- `debian_linux = 8.0`\n- `debian_linux = 9.0`\n- `fedora = 29`\n- `fedora = 30`\n- `leap = 15.0`\n- `leap = 15.1`\n- `hospitality_res_3700 >= 5.7, <= 5.7.6`\n- `http_server = 12.1.3.0`\n- `http_server = 12.2.1.4.0`\n- `outside_in_technology = 8.5.4`\n- `outside_in_technology = 8.5.5`\n- `nessus < 8.15.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `libexpat 2.2.7`\n- `nessus 8.15.0`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":41.3,"likelihood":1.4,"exploitation":0,"ransomware":0},"changes":[]}