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Vulnerability record · CVE-2018-20843 · published 24 June 2019

CVE-2018-20843: Libexpat project libexpat xml external entity (xxe) vulnerability

LLibexpat Project · Libexpat

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).

7.5 CVSS 3.1 High EPSS 7.1% · top 6.0% CWE-611 · XML external entity (XXE)
7.5CVSS 3.1 base score, v2 7.8
7.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
9Affected product versions listed by NVD
42References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

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).

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

9 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00039.html Mailing ListThird Party Advisory
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5226 Issue TrackingThird Party Advisory
https://github.com/libexpat/libexpat/blob/R_2_2_7/expat/Changes Release NotesThird Party Advisory
https://github.com/libexpat/libexpat/issues/186 Issue TrackingPatchThird Party Advisory
https://github.com/libexpat/libexpat/pull/262 ExploitPatchThird Party Advisory
https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6 PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2019/06/msg00028.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CEJJSQSG3KSUQY4FPVHZ7ZT
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IDAUGEB3TUP6NEKJDBUBZX7
https://seclists.org/bugtraq/2019/Jun/39 Mailing ListThird 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 PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpuapr2020.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpuoct2020.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html PatchThird 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 ListThird Party Advisory
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5226 Issue TrackingThird Party Advisory
https://github.com/libexpat/libexpat/blob/R_2_2_7/expat/Changes Release NotesThird Party Advisory
https://github.com/libexpat/libexpat/issues/186 Issue TrackingPatchThird Party Advisory
https://github.com/libexpat/libexpat/pull/262 ExploitPatchThird Party Advisory
https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6 PatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2019/06/msg00028.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CEJJSQSG3KSUQY4FPVHZ7ZT
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IDAUGEB3TUP6NEKJDBUBZX7
https://seclists.org/bugtraq/2019/Jun/39 Mailing ListThird 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 PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpuapr2020.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpuoct2020.html PatchThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2018-20843), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.