Toddr: Security Vulnerabilities
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
CVSS Score
9.8
EPSS Score
0.0
Published
2026-03-19
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.
CVSS Score
7.5
EPSS Score
0.0
Published
2026-03-19
YAML::Syck versions through 1.36 for Perl has several potential security vulnerabilities including a high-severity heap buffer overflow in the YAML emitter.
The heap overflow occurs when class names exceed the initial 512-byte allocation.
The base64 decoder could read past the buffer end on trailing newlines.
strtok mutated n->type_id in place, corrupting shared node data.
A memory leak occurred in syck_hdlr_add_anchor when a node already had an anchor. The incoming anchor string 'a' was leaked on early return.
CVSS Score
9.1
EPSS Score
0.0
Published
2026-03-16
YAML::Syck versions before 1.36 for Perl has missing null-terminators which causes out-of-bounds read and potential information disclosure
Missing null terminators in token.c leads to but-of-bounds read which allows adjacent variable to be read
The issue is seen with complex YAML files with a hash of all keys and empty values. There is no indication that the issue leads to accessing memory outside that allocated to the module.
CVSS Score
6.5
EPSS Score
0.0
Published
2025-10-16