libxml2 2.6.32 and earlier does not properly detect recursion during entity expansion in an attribute value, which allows context-dependent attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document.

Multiple buffer overflows in libXML 2.6.12 and 2.6.13 (libxml2), and possibly other versions, may allow remote attackers to execute arbitrary code via (1) a long FTP URL that is not properly handled by the xmlNanoFTPScanURL function, (2) a long proxy URL containing FTP data that is not properly handled by the xmlNanoFTPScanProxy function, and other overflows related to manipulation of DNS length values, including (3) xmlNanoFTPConnect, (4) xmlNanoHTTPConnectHost, and (5) xmlNanoHTTPConnectHost.

Buffer overflow in the (1) nanohttp or (2) nanoftp modules in XMLSoft Libxml 2 (Libxml2) 2.6.0 through 2.6.5 allow remote attackers to execute arbitrary code via a long URL.

libxml2, possibly before 2.5.0, does not properly detect recursion during entity expansion, which allows context-dependent attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document containing a large number of nested entity references, aka the "billion laughs attack."