CVE-2018-20843

expat: large number of colons in input makes parser consume high amount of resources, leading to DoS

Severity Score

7.5

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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).

En libexpat en Expat anterior a versión 2.2.7, una entrada XML incluyendo nombres XML que contienen una gran cantidad de "dos puntos", podría hacer que el analizador XML consuma una gran cantidad de recursos de RAM y CPU durante el procesamiento (lo suficiente como para ser utilizables en ataques de denegación de servicio) .

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.

Red Hat JBoss Core Services is a set of supplementary software for Red Hat JBoss middleware products. This software, such as Apache HTTP Server, is common to multiple JBoss middleware products, and is packaged under Red Hat JBoss Core Services to allow for faster distribution of updates, and for a more consistent update experience. This release adds the new Apache HTTP Server 2.4.37 Service Pack 3 packages that are part of the JBoss Core Services offering. This release serves as a replacement for Red Hat JBoss Core Services Pack Apache Server 2.4.37 Service Pack 2 and includes bug fixes and enhancements. Issues addressed include buffer over-read, denial of service, and memory leak vulnerabilities.

*Credits: N/A

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Complete

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2019-06-24 CVE Reserved
2019-06-24 CVE Published
2024-08-05 CVE Updated
2024-08-05 First Exploit
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-400: Uncontrolled Resource Consumption
CWE-611: Improper Restriction of XML External Entity Reference

CAPEC

References (23)

URL	Tag	Source
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5226	Issue Tracking
https://github.com/libexpat/libexpat/blob/R_2_2_7/expat/Changes	Release Notes
https://lists.debian.org/debian-lts-announce/2019/06/msg00028.html	Mailing List
https://seclists.org/bugtraq/2019/Jun/39	Mailing List
https://security.netapp.com/advisory/ntap-20190703-0001	Third Party Advisory
https://support.f5.com/csp/article/K51011533	Third Party Advisory
https://www.tenable.com/security/tns-2021-11	Third Party Advisory

URL	Date	SRC
https://github.com/libexpat/libexpat/pull/262	2024-08-05

URL	Date	SRC
https://github.com/libexpat/libexpat/issues/186	2023-11-07
https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6	2023-11-07
https://www.oracle.com/security-alerts/cpuApr2021.html	2023-11-07
https://www.oracle.com/security-alerts/cpuapr2020.html	2023-11-07
https://www.oracle.com/security-alerts/cpuoct2020.html	2023-11-07
https://www.oracle.com/security-alerts/cpuoct2021.html	2023-11-07

URL	Date	SRC
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00039.html	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CEJJSQSG3KSUQY4FPVHZ7ZTT7FORMFVD	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IDAUGEB3TUP6NEKJDBUBZX7N5OAUOOOK	2023-11-07
https://security.gentoo.org/glsa/201911-08	2023-11-07
https://usn.ubuntu.com/4040-1	2023-11-07
https://usn.ubuntu.com/4040-2	2023-11-07
https://www.debian.org/security/2019/dsa-4472	2023-11-07
https://access.redhat.com/security/cve/CVE-2018-20843	2021-03-22
https://bugzilla.redhat.com/show_bug.cgi?id=1723723	2021-03-22

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Libexpat Project Search vendor "Libexpat Project"		Libexpat Search vendor "Libexpat Project" for product "Libexpat"				< 2.2.7 Search vendor "Libexpat Project" for product "Libexpat" and version " < 2.2.7"		-		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				12.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "12.04"		-		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				14.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "14.04"		esm		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				16.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "16.04"		lts		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				18.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "18.04"		lts		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				18.10 Search vendor "Canonical" for product "Ubuntu Linux" and version "18.10"		-		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				19.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "19.04"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				8.0 Search vendor "Debian" for product "Debian Linux" and version "8.0"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				9.0 Search vendor "Debian" for product "Debian Linux" and version "9.0"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				29 Search vendor "Fedoraproject" for product "Fedora" and version "29"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				30 Search vendor "Fedoraproject" for product "Fedora" and version "30"		-		Affected
Opensuse Search vendor "Opensuse"		Leap Search vendor "Opensuse" for product "Leap"				15.0 Search vendor "Opensuse" for product "Leap" and version "15.0"		-		Affected
Opensuse Search vendor "Opensuse"		Leap Search vendor "Opensuse" for product "Leap"				15.1 Search vendor "Opensuse" for product "Leap" and version "15.1"		-		Affected
Oracle Search vendor "Oracle"		Hospitality Res 3700 Search vendor "Oracle" for product "Hospitality Res 3700"				>= 5.7 <= 5.7.6 Search vendor "Oracle" for product "Hospitality Res 3700" and version " >= 5.7 <= 5.7.6"		-		Affected
Oracle Search vendor "Oracle"		Http Server Search vendor "Oracle" for product "Http Server"				12.1.3.0 Search vendor "Oracle" for product "Http Server" and version "12.1.3.0"		-		Affected
Oracle Search vendor "Oracle"		Http Server Search vendor "Oracle" for product "Http Server"				12.2.1.4.0 Search vendor "Oracle" for product "Http Server" and version "12.2.1.4.0"		-		Affected
Oracle Search vendor "Oracle"		Outside In Technology Search vendor "Oracle" for product "Outside In Technology"				8.5.4 Search vendor "Oracle" for product "Outside In Technology" and version "8.5.4"		-		Affected
Oracle Search vendor "Oracle"		Outside In Technology Search vendor "Oracle" for product "Outside In Technology"				8.5.5 Search vendor "Oracle" for product "Outside In Technology" and version "8.5.5"		-		Affected
Tenable Search vendor "Tenable"		Nessus Search vendor "Tenable" for product "Nessus"				< 8.15.0 Search vendor "Tenable" for product "Nessus" and version " < 8.15.0"		-		Affected