--- 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' --- ## Overview 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 attacks). ## 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` ## Remediation Upgrade past the affected range: - `libexpat 2.2.7` - `nessus 8.15.0`