#VU52736 Reachable Assertion in ISC BIND

Published: 2021-04-29

Vulnerability identifier: #VU52736

Vulnerability 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


Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Server applications / DNS servers

Vendor: ISC


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.

Install updates from vendor's website.

Vulnerable software versions

ISC BIND: 9.0 - 9.17.11

External links

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.

Latest bulletins with this vulnerability