libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_GetBuffer, XML_Parse, XML_ParseBuffer, XML_ParserFree, or XML_ParserReset from within handlers in cases of a policy violation. Thus, a use-after-free can occur,
In libexpat before 2.8.1, the computational complexity of attribute name collision checks allows a denial of service via moderately sized crafted XML input.
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.