Debian Security Advisory

DLA-2647-1 bind9 -- LTS security update

Date Reported:
04 May 2021
Affected Packages:
Security database references:
In the Debian bugtracking system: Bug 987741, Bug 987742, Bug 987743.
In Mitre's CVE dictionary: CVE-2021-25214, CVE-2021-25215, CVE-2021-25216.
More information:

Several vulnerabilities were discovered in BIND, a DNS server implementation.

  • 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 Debian 9 stretch, these problems have been fixed in version 1:9.10.3.dfsg.P4-12.3+deb9u9.

We recommend that you upgrade your bind9 packages.

For the detailed security status of bind9 please refer to its security tracker page at:

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: