Debian update for bind9

1) Reachable Assertion

EUVDB-ID: #VU52734

Risk: Low

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-25214

CWE-ID: CWE-617 - Reachable Assertion

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a reachable assertion when pressing IXFR queries. An IXFR stream containing SOA records with an owner name other than the transferred zone's apex may cause the receiving named server to inadvertently remove the SOA record for the zone in question from the zone database. This leads to an assertion failure when the next SOA refresh query for that zone is made. When a vulnerable version of named receives a malformed IXFR triggering the flaw described above, the named process will terminate due to a failed assertion the next time the transferred secondary zone is refreshed.

Mitigation

Update bind9 package to version 1:9.11.5.P4+dfsg-5.1+deb10u5.

Vulnerable software versions

bind9 (Debian package): 1:9.11.5.P4+dfsg-5.1+deb10u1 - 9.11.5.P4+dfsg-5.1+deb10u2

External links

http://www.debian.org/security/2021/dsa-4909

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Reachable Assertion

EUVDB-ID: #VU52736

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-25215

CWE-ID: CWE-617 - Reachable Assertion

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a reachable assertion when processing DNAME records. A remote attacker can force named to add the same RRset to the ANSWER section more than once, trigger an assertion failure and crash the service. Both authoritative and recursive servers are affected by this issue during zone transfers.

Mitigation

Update bind9 package to version 1:9.11.5.P4+dfsg-5.1+deb10u5.

Vulnerable software versions

bind9 (Debian package): 1:9.11.5.P4+dfsg-5.1+deb10u1 - 9.11.5.P4+dfsg-5.1+deb10u2

External links

http://www.debian.org/security/2021/dsa-4909

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

3) Buffer overflow

EUVDB-ID: #VU52737

Risk: High

CVSSv3.1: 7.1 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-25216

CWE-ID: CWE-119 - Memory corruption

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error within the GSS-TSIG extension. A remote attacker can send specially crafted requests to the server, trigger buffer overflow and execute arbitrary code on the system.

Successful exploitation of the vulnerability requires that named is configure to use SPNEGO implementation by setting values for the tkey-gssapi-keytab or tkey-gssapi-credential configuration options (often used with Samba as well as in mixed-server environments that combine BIND servers with Active Directory domain controllers).

Mitigation

Update bind9 package to version 1:9.11.5.P4+dfsg-5.1+deb10u5.

Vulnerable software versions

bind9 (Debian package): 1:9.11.5.P4+dfsg-5.1+deb10u1 - 9.11.5.P4+dfsg-5.1+deb10u2

External links

http://www.debian.org/security/2021/dsa-4909

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.