https://github.com/libexpat/libexpat/pull/1331 reports:
Expat through 2.8.3 contains an out-of-bounds read vulnerability
that allows attackers to trigger memory corruption by processing
XML with external entity parsers created via
XML_ExternalEntityParserCreate. A struct size mismatch between
ELEMENT_TYPE members causes storeAtts to read the attIndex member
past allocated memory boundaries, resulting in failure to normalize
whitespace in non-CDATA attributes or a wild pointer dereference
causing a segfault. This vulnerability was introduced by the fix
for CVE-2026-66046.