CVE-2018-20843

7.5 high SSVC exploitation: none Modified

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).

Fix

Patch, vendor advisory and mitigation references on NVD 14

https://github.com/libexpat/libexpat/issues/186 Issue Tracking, Patch, Third Party Advisory
https://github.com/libexpat/libexpat/pull/262 Exploit, Patch, Third Party Advisory
https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6 Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuApr2021.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2020.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2020.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Patch, Third Party Advisory
https://github.com/libexpat/libexpat/issues/186 Issue Tracking, Patch, Third Party Advisory
https://github.com/libexpat/libexpat/pull/262 Exploit, Patch, Third Party Advisory
https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6 Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuApr2021.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2020.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2020.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Patch, Third Party Advisory

Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.

Change history 1

2026-10-15 00:45First seenCVSS 7.5 · libexpat_project, canonical, debianNVD modified 2026-10-14 07:16

Affected (CPE criteria) 19

cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:-:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:19.04:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:29:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.0:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
cpe:2.3:a:oracle:hospitality_res_3700:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:http_server:12.1.3.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:http_server:12.2.1.4.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:outside_in_technology:8.5.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:outside_in_technology:8.5.5:*:*:*:*:*:*:*
cpe:2.3:a:tenable:nessus:*:*:*:*:*:*:*:*

References 43

http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00039.html Mailing List, Third Party Advisory
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5226 Issue Tracking, Third Party Advisory
https://github.com/libexpat/libexpat/blob/R_2_2_7/expat/Changes Release Notes, Third Party Advisory
https://github.com/libexpat/libexpat/issues/186 Issue Tracking, Patch, Third Party Advisory
https://github.com/libexpat/libexpat/pull/262 Exploit, Patch, Third Party Advisory
https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6 Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/06/msg00028.html Mailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CEJJSQSG3KSUQY4FPVHZ7ZTT7FORMFVD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IDAUGEB3TUP6NEKJDBUBZX7N5OAUOOOK/
https://seclists.org/bugtraq/2019/Jun/39 Mailing List, Third Party Advisory
https://security.gentoo.org/glsa/201911-08 Third Party Advisory
https://security.netapp.com/advisory/ntap-20190703-0001/ Third Party Advisory
https://support.f5.com/csp/article/K51011533 Third Party Advisory
https://usn.ubuntu.com/4040-1/ Third Party Advisory
https://usn.ubuntu.com/4040-2/ Third Party Advisory
https://www.debian.org/security/2019/dsa-4472 Third Party Advisory
https://www.oracle.com/security-alerts/cpuApr2021.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2020.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2020.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Patch, Third Party Advisory
https://www.tenable.com/security/tns-2021-11 Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00039.html Mailing List, Third Party Advisory
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5226 Issue Tracking, Third Party Advisory
https://github.com/libexpat/libexpat/blob/R_2_2_7/expat/Changes Release Notes, Third Party Advisory
https://github.com/libexpat/libexpat/issues/186 Issue Tracking, Patch, Third Party Advisory
https://github.com/libexpat/libexpat/pull/262 Exploit, Patch, Third Party Advisory
https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6 Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/06/msg00028.html Mailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CEJJSQSG3KSUQY4FPVHZ7ZTT7FORMFVD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IDAUGEB3TUP6NEKJDBUBZX7N5OAUOOOK/
https://seclists.org/bugtraq/2019/Jun/39 Mailing List, Third Party Advisory
https://security.gentoo.org/glsa/201911-08 Third Party Advisory
https://security.netapp.com/advisory/ntap-20190703-0001/ Third Party Advisory
https://support.f5.com/csp/article/K51011533 Third Party Advisory
https://usn.ubuntu.com/4040-1/ Third Party Advisory
https://usn.ubuntu.com/4040-2/ Third Party Advisory
https://www.debian.org/security/2019/dsa-4472 Third Party Advisory
https://www.oracle.com/security-alerts/cpuApr2021.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2020.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2020.html Patch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Patch, Third Party Advisory
https://www.tenable.com/security/tns-2021-11 Third Party Advisory
https://cert-portal.siemens.com/productcert/html/ssa-398330.html