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.

Description

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.

Affected Products

References

• https://github.com/cpan-authors/XML-Parser/commit/56b0509dfc6b559cd7555ea81ee62e3622069255.patch
• https://github.com/cpan-authors/XML-Parser/issues/64(Issue Tracking)
• https://metacpan.org/release/TODDR/XML-Parser-2.46/changes
• https://rt.cpan.org/Ticket/Display.html?id=19859(Mailing List)
• http://www.openwall.com/lists/oss-security/2026/03/19/1(Mailing List, Patch, Third Party Advisory)
• http://www.openwall.com/lists/oss-security/2026/03/22/3