libxml2: Fix CVE-2025-49794 & CVE-2025-49796

libxml2: Fix CVE-2025-49794 & CVE-2025-49796

A use-after-free vulnerability was found in libxml2. This issue
occurs when parsing XPath elements under certain circumstances
when the XML schematron has the <sch:name path="..."/> schema
elements. This flaw allows a malicious actor to craft a malicious
XML document used as input for libxml, resulting in the program's
crash using libxml or other possible undefined behaviors.

A vulnerability was found in libxml2. Processing certain sch:name
elements from the input XML file can trigger a memory corruption
issue. This flaw allows an attacker to craft a malicious XML input
file that can lead libxml to crash, resulting in a denial of service
or other possible undefined behavior due to sensitive data being
corrupted in memory.

References:
https://security-tracker.debian.org/tracker/CVE-2025-49794
https://security-tracker.debian.org/tracker/CVE-2025-49796

Upstream-patch:
https://gitlab.gnome.org/GNOME/libxml2/-/commit/71e1e8af5ee46dad1b57bb96cfbf1c3ad21fbd7b

Signed-off-by: Divya Chellam <divya.chellam@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>