CVE-2013-0340
MediumExploitation Probability (EPSS)
Very high risk97th percentile - higher than 97% of all known CVEs
Summary
expat before version 2.4.0 does not properly handle entities expansion unless an application developer uses the XML_SetEntityDeclHandler function. This 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.
Risk Assessment
Attackers can exploit the vulnerability to leak sensitive files, scan the internal network, or cause a denial of service. This can lead to data disclosure and disruption of XML-processing applications.
Recommendation
Update the expat library to version 2.4.0 or later. In XML-processing applications, disable external entity expansion or use the XML_SetEntityDeclHandler function for safe handling.
Other vulnerabilities in expat
See all- CVE-2022-25315Critical
In Expat (aka libexpat) before 2.4.5, there is an integer overflow in storeRawNames.
- CVE-2022-25314High
In Expat (libexpat) before 2.4.5, there is an integer overflow in copyString.
- CVE-2022-25236Critical
In xmlparse.c in Expat (aka libexpat) before 2.4.5, attackers can insert namespace-separator characters into namespace URIs.
- CVE-2022-25235Critical
In xmltok_impl.c in Expat (aka libexpat) before 2.4.5 lacks certain validation of encoding, such as checks for whether a UTF-8 character is valid in a certain context.
- CVE-2022-23990High
Expat (libexpat) before 2.4.4 has an integer overflow in the doProlog function. This may lead to improper XML parser behavior.
- CVE-2022-23852Critical
Expat (aka libexpat) before 2.4.4 has a signed integer overflow in XML_GetBuffer, for configurations with a nonzero XML_CONTEXT_BYTES.
- CVE-2022-22824Critical
The defineAttribute function in xmlparse.c in Expat (libexpat) before 2.4.3 has an integer overflow. This may lead to incorrect behavior of the XML parser.
- CVE-2022-22823Critical
The build_model function in xmlparse.c in Expat (libexpat) before 2.4.3 has an integer overflow. This may lead to incorrect behavior of the XML parser.
- CVE-2022-22822Critical
addBinding in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.
- CVE-2021-45960High
In Expat (libexpat) before 2.4.3, a left shift by 29 or more bits in the storeAtts function in xmlparse.c can lead to realloc misbehavior, such as allocating too few bytes or only freeing memory.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS