expat before version 2.4.0 does not properly handle entities expansion...

Vulnerability Description

expat before version 2.4.0 does not properly handle entities expansion unless an application developer uses the XML_SetEntityDeclHandler function, which allows remote attackers to cause a denial of service (resource consumption), send HTTP requests to intranet servers, or read arbitrary files via a crafted XML document, aka an XML External Entity (XXE) issue. NOTE: it could be argued that because expat already provides the ability to disable external entity expansion, the responsibility for resolving this issue lies with application developers; according to this argument, this entry should be REJECTed, and each affected application would need its own CVE.

References

• http://openwall.com/lists/oss-security/2013/02/22/3
• http://www.openwall.com/lists/oss-security/2013/04/12/6
• http://www.osvdb.org/90634
• http://securitytracker.com/id?1028213
• https://security.gentoo.org/glsa/201701-21
• http://www.securityfocus.com/bid/58233
• https://support.apple.com/kb/HT212805
• https://support.apple.com/kb/HT212804
• https://support.apple.com/kb/HT212807
• https://support.apple.com/kb/HT212819
• https://support.apple.com/kb/HT212814
• https://support.apple.com/kb/HT212815
• http://seclists.org/fulldisclosure/2021/Sep/33
• http://seclists.org/fulldisclosure/2021/Sep/34
• http://seclists.org/fulldisclosure/2021/Sep/40
• http://seclists.org/fulldisclosure/2021/Sep/35
• http://seclists.org/fulldisclosure/2021/Sep/38
• http://seclists.org/fulldisclosure/2021/Sep/39
• https://lists.apache.org/thread.html/r41eca5f4f09e74436cbb05dec450fc2bef37b5d3e966aa7cc5fada6d%40%3Cannounce.apache.org%3E
• https://lists.apache.org/thread.html/rfb2c193360436e230b85547e85a41bea0916916f96c501f5b6fc4702%40%3Cusers.openoffice.apache.org%3E
• http://www.openwall.com/lists/oss-security/2021/10/07/4
• http://seclists.org/fulldisclosure/2021/Oct/62
• http://seclists.org/fulldisclosure/2021/Oct/63
• http://seclists.org/fulldisclosure/2021/Oct/61
• https://github.com/libexpat/libexpat/blob/R_2_4_1/expat/Changes