CVE-2018-20843: XEE
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).
Other sources
It was discovered that the "setElementTypePrefix()" function incorrectly extracted XML namespace prefixes. By tricking an application into processing a specially crafted XML file, an attacker could cause unusually high consumption of memory resources and possibly lead to a denial of service.
libexpat is vulnerable to a denial of service, caused by an error in the XML parser. By persuading a victim to open a specially-crafted file, a remote attacker could exploit this vulnerability to consume all available CPU resources.
— IBM
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
redhat/jbcs-httpd24-curlto a version that resolves this vulnerability.Fixed in 0:7.64.1-36.jbcs.el6 - Upgrade
Upgrade
redhat/jbcs-httpd24-httpdto a version that resolves this vulnerability.Fixed in 0:2.4.37-57.jbcs.el6 - Upgrade
Upgrade
redhat/jbcs-httpd24-nghttp2to a version that resolves this vulnerability.Fixed in 0:1.39.2-25.jbcs.el6 - Upgrade
Upgrade
redhat/jbcs-httpd24-curlto a version that resolves this vulnerability.Fixed in 0:7.64.1-36.jbcs.el7 - Upgrade
Upgrade
redhat/jbcs-httpd24-httpdto a version that resolves this vulnerability.Fixed in 0:2.4.37-57.jbcs.el7 - Upgrade
Upgrade
redhat/jbcs-httpd24-nghttp2to a version that resolves this vulnerability.Fixed in 0:1.39.2-25.jbcs.el7 - Upgrade
Upgrade
redhat/jbcs-httpd24-openssl-pkcs11to a version that resolves this vulnerability.Fixed in 0:0.4.10-7.jbcs.el7 - Upgrade
Upgrade
redhat/expatto a version that resolves this vulnerability.Fixed in 0:2.1.0-12.el7 - Upgrade
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redhat/mingw-expatto a version that resolves this vulnerability.Fixed in 0:2.2.4-5.el8 - Upgrade
Upgrade
redhat/expatto a version that resolves this vulnerability.Fixed in 0:2.2.5-4.el8 - Upgrade
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debian/expatto a version that resolves this vulnerability.Fixed in 2.2.6-2Fixed in 2.2.0-2+deb9u2 - Upgrade
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redhat/expatto a version that resolves this vulnerability.Fixed in 2.2.7 - Upgrade
Upgrade
debian/expatto a version that resolves this vulnerability.Fixed in 2.5.0-1+deb12u2Fixed in 2.5.0-1+deb12u4Fixed in 2.8.3-1~deb13u1Fixed in 2.9.0-1 - Upgrade
Upgrade
libexpatto a version that resolves this vulnerability.Fixed in 2.2.7
Event History
Parent advisories
This vulnerability appears in the following advisories.
Frequently Asked Questions
What is the severity of CVE-2018-20843?
CVE-2018-20843 has been classified as a high-severity vulnerability due to its potential to cause denial-of-service attacks by consuming excessive resources.
How do I fix CVE-2018-20843?
To fix CVE-2018-20843, update your libexpat version to 2.2.7 or later as recommended by your software provider.
What software is affected by CVE-2018-20843?
CVE-2018-20843 affects several versions of libexpat, particularly versions prior to 2.2.7, along with specific Red Hat packages like jbcs-httpd24-curl and jbcs-httpd24-httpd.
What are the symptoms of CVE-2018-20843 exploitation?
Exploitation of CVE-2018-20843 may result in the XML parser consuming high amounts of RAM and CPU resources, leading to performance degradation or application crashes.
Is CVE-2018-20843 present in my system?
To determine if CVE-2018-20843 is present in your system, check the version of the libexpat library and any affected software packages installed.