Vulnerability identifier: #VU52737

Vulnerability 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

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
ISC BIND
Server applications / DNS servers

Vendor: ISC

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
Install updates from vendor's website.

Vulnerable software versions

ISC BIND: 9.5.0 - 9.17.1

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External links
http://kb.isc.org/v1/docs/cve-2021-25215
http://www.openwall.com/lists/oss-security/2021/04/29/1

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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.