Denial of service in MIT Kerberos 5

1) Uncontrolled Recursion

EUVDB-ID: #VU48444

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-2020-28196

CWE-ID: CWE-674 - Uncontrolled Recursion

Exploit availability: No

Description

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

The vulnerability exists due to uncontrolled recursion in MIT Kerberos 5 (aka krb5) implementation when processing ASN.1-encoded Kerberos messages in lib/krb5/asn.1/asn1_encode.c. A remote attacker can pass specially crafted data to the application that uses Kerberos and perform a denial of service (DoS) attack.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Kerberos 5: 1.17 - 1.18.2

External links

http://github.com/krb5/krb5/commit/57415dda6cf04e73ffc3723be518eddfae599bfd
http://lists.debian.org/debian-lts-announce/2020/11/msg00011.html
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/73IGOG6CZAVMVNS4GGRMOLOZ7B6QVA7F/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/KPH2V3WSQTELROZK3GFCPQDOFLKIZ6H5/
http://security.gentoo.org/glsa/202011-17

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.