The big2_toUtf8 function in lib/xmltok.c in libexpat in Expat 2.0.1, as used in the XML-Twig module for Perl, allows context-dependent attackers to cause a denial of service (application crash) via an XML document with malformed UTF-8 sequences that trigger a buffer over-read, related to the doProlog function in lib/xmlparse.c, a different vulnerability than CVE-2009-2625 and CVE-2009-3720.

The XML parser (xmlparse.c) in expat before 2.1.0 computes hash values without restricting the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via an XML file with many identifiers with the same value.

readfilemap.c in expat before 2.1.0 allows context-dependent attackers to cause a denial of service (file descriptor consumption) via a large number of crafted XML files.

Memory leak in the poolGrow function in expat/lib/xmlparse.c in expat before 2.1.0 allows context-dependent attackers to cause a denial of service (memory consumption) via a large number of crafted XML files that cause improperly-handled reallocation failures when expanding entities.

Expat, when used in a parser that has not called XML_SetHashSalt or passed it a seed of 0, makes it easier for context-dependent attackers to defeat cryptographic protection mechanisms via vectors involving use of the srand function.

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.

Multiple integer overflows in the XML_GetBuffer function in Expat through 2.1.0, as used in Google Chrome before 44.0.2403.89 and other products, allow remote attackers to cause a denial of service (heap-based buffer overflow) or possibly have unspecified other impact via crafted XML data, a related issue to CVE-2015-2716.

Expat allows context-dependent attackers to cause a denial of service (crash) or possibly execute arbitrary code via a malformed input document, which triggers a buffer overflow.

The overflow protection in Expat is removed by compilers with certain optimization settings, which allows remote attackers to cause a denial of service (crash) or possibly execute arbitrary code via crafted XML data. NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-1283 and CVE-2015-2716.

The XML parser in Expat does not use sufficient entropy for hash initialization, which allows context-dependent attackers to cause a denial of service (CPU consumption) via crafted identifiers in an XML document. NOTE: this vulnerability exists because of an incomplete fix for CVE-2012-0876.

The writeRandomBytes_RtlGenRandom function in xmlparse.c in libexpat in Expat 2.2.1 and 2.2.2 on Windows allows local users to gain privileges via a Trojan horse ADVAPI32.DLL in the current working directory because of an untrusted search path, aka DLL hijacking.

XML External Entity vulnerability in libexpat 2.2.0 and earlier (Expat XML Parser Library) allows attackers to put the parser in an infinite loop using a malformed external entity definition from an external DTD.

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).

In libexpat before 2.2.8, crafted XML input could fool the parser into changing from DTD parsing to document parsing too early; a consecutive call to XML_GetCurrentLineNumber (or XML_GetCurrentColumnNumber) then resulted in a heap-based buffer over-read.

In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in the storeAtts function in xmlparse.c can lead to realloc misbehavior (e.g., allocating too few bytes, or only freeing memory).

In doProlog in xmlparse.c in Expat (aka libexpat) before 2.4.3, an integer overflow exists for m_groupSize.

addBinding in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

build_model in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

defineAttribute in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

lookup in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

nextScaffoldPart in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

storeAtts in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.

Expat (aka libexpat) before 2.4.4 has a signed integer overflow in XML_GetBuffer, for configurations with a nonzero XML_CONTEXT_BYTES.

Expat (aka libexpat) before 2.4.4 has an integer overflow in the doProlog function.

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.

xmlparse.c in Expat (aka libexpat) before 2.4.5 allows attackers to insert namespace-separator characters into namespace URIs.

In Expat (aka libexpat) before 2.4.5, an attacker can trigger stack exhaustion in build_model via a large nesting depth in the DTD element.

In Expat (aka libexpat) before 2.4.5, there is an integer overflow in copyString.

In Expat (aka libexpat) before 2.4.5, there is an integer overflow in storeRawNames.

libexpat before 2.4.9 has a use-after-free in the doContent function in xmlparse.c.

In libexpat through 2.4.9, there is a use-after free caused by overeager destruction of a shared DTD in XML_ExternalEntityParserCreate in out-of-memory situations.

libexpat through 2.5.0 allows a denial of service (resource consumption) because many full reparsings are required in the case of a large token for which multiple buffer fills are needed.

libexpat through 2.5.0 allows recursive XML Entity Expansion if XML_DTD is undefined at compile time.

libexpat through 2.6.1 allows an XML Entity Expansion attack when there is isolated use of external parsers (created via XML_ExternalEntityParserCreate).

An issue was discovered in libexpat before 2.6.3. xmlparse.c does not reject a negative length for XML_ParseBuffer.

An issue was discovered in libexpat before 2.6.3. dtdCopy in xmlparse.c can have an integer overflow for nDefaultAtts on 32-bit platforms (where UINT_MAX equals SIZE_MAX).

An issue was discovered in libexpat before 2.6.3. nextScaffoldPart in xmlparse.c can have an integer overflow for m_groupSize on 32-bit platforms (where UINT_MAX equals SIZE_MAX).

An issue was discovered in libexpat before 2.6.4. There is a crash within the XML_ResumeParser function because XML_StopParser can stop/suspend an unstarted parser.

libexpat in Expat before 2.7.2 allows attackers to trigger large dynamic memory allocations via a small document that is submitted for parsing.

In libexpat through 2.7.3, a crafted file with an approximate size of 2 MiB can lead to dozens of seconds of processing time.

In libexpat before 2.7.4, XML_ExternalEntityParserCreate does not copy unknown encoding handler user data.

In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize because there is no integer overflow check for tag buffer reallocation.

libexpat before 2.7.5 allows a NULL pointer dereference with empty external parameter entity content.

libexpat before 2.7.5 allows an infinite loop while parsing DTD content.

libexpat before 2.7.5 allows a NULL pointer dereference in the function setContext on retry after an earlier ouf-of-memory condition.

libexpat before 2.8.0 uses insufficient entropy, and thus hash flooding can occur via a crafted XML document.