Debian: DSA-4265-1 Critical: Apache XML Security Denial Of Service

It was discovered that the Apache XML Security for C++ library performed
insufficient validation of KeyInfo hints, which could result in denial
of service via NULL pointer dereferences when processing malformed XML
data.

For the stable distribution (stretch), this problem has been fixed in
version 1.7.3-4+deb9u1.

We recommend that you upgrade your xml-security-c packages.

For the detailed security status of xml-security-c please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/source-package/xml-security-c

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/