XML::Parser versions through 2.45 for Perl could overflow the pre-allocated buffer size cause a heap corruption (double free or corruption) and crashes.
A :utf8 PerlIO layer, parse_stream() in Expat.xs could overflow the XML input buffer because Perl's read() returns decoded characters while SvPV() gives back multi-byte UTF-8 bytes that can exceed the pre-allocated buffer size. This can cause heap corruption (double free or corruption) and crashes.
XML::Parser versions through 2.47 for Perl has an off-by-one heap buffer overflow in st_serial_stack.
In the case (stackptr == stacksize - 1), the stack will NOT be expanded. Then the new value will be written at location (++stackptr), which equals stacksize and therefore falls just outside the allocated buffer.
The bug can be observed when parsing an XML file with very deep element nesting
Now using Version 1990709 of expat. No local patches.
Numerous people reported a SEGV problem when running t/cdata on various platforms and versions of perl. The problem was introduced with the setHandlers change. In some cases an un-initialized value was being returned.
Added an additional external entity handler, lwp_ext_ent_handler, that deals with general URIs. It is installed instead of the "file only" handler if the LWP package is installed.