#VU55974 Reachable Assertion in ISC BIND


Published: 2021-08-18

Vulnerability identifier: #VU55974

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-2021-25218

CWE-ID: CWE-617

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
ISC BIND
Server applications / DNS servers

Vendor: ISC

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.

Is there known malware, which exploits this vulnerability?

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


Latest bulletins with this vulnerability