Vulnerabilities fixed in libxml2-2.15.4

<p>Posted by Sam James on Sep 04</p>From libxml2-2.15.4:<br /> <br /> +v2.15.4: Sep 01 2026<br /> +<br /> +### Security<br /> +<br /> +- xmlregexp: Prevent out-of-bounds read in NXT macro<br /> +- fix: add missing overflow checks in dict.c, uri.c, and valid.c<br /> +- xmlregexp: Calc string length after null checking<br /> +- xpointer: Check overflow in xmlXPtrEvalXPtrPart<br /> +- xmlIO: Check fo