Debian Security Advisory: DSA-4909-1 Regarding Critical Bind9 DoS

CVE-2021-25214

Greg Kuechle discovered that a malformed incoming IXFR transfer
could trigger an assertion failure in named, resulting in denial
of service.

CVE-2021-25215

Siva Kakarla discovered that named could crash when a DNAME record
placed in the ANSWER section during DNAME chasing turned out to be
the final answer to a client query.

CVE-2021-25216

It was discovered that the SPNEGO implementation used by BIND is
prone to a buffer overflow vulnerability. This update switches to
use the SPNEGO implementation from the Kerberos libraries.

For the stable distribution (buster), these problems have been fixed in
version 1:9.11.5.P4+dfsg-5.1+deb10u5.

We recommend that you upgrade your bind9 packages.

For the detailed security status of bind9 please refer to its security
tracker page at:
https://security-tracker.debian.org/tracker/source-package/bind9

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