Denial of service in ISC BIND

1) Reachable Assertion

EUVDB-ID: #VU55974

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-2021-25218

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 sending large responses over UDP. If named attempts to respond over UDP with a response that is larger than the current effective interface maximum transmission unit (MTU), and if response-rate limiting (RRL) is active, an assertion failure is triggered. A remote attacker can force named to trigger the assertion failure and perform a denial of service attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

ISC BIND: 9.16.19 - 9.17.16

External links

http://kb.isc.org/v1/docs/cve-2021-25218

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

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