Denial of service in MIT Kerberos 5

1) NULL pointer dereference

EUVDB-ID: #VU55287

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-2021-36222

CWE-ID: CWE-476 - NULL Pointer Dereference

Exploit availability: No

Description

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

The vulnerability exists due to a NULL pointer dereference error in kdc/kdc_preauth_ec.c in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5). A remote attacker can send a request containing a PA-ENCRYPTED-CHALLENGE padata element without using FAST and perform a denial of service (DoS) attack.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Kerberos 5: 1.2 - 1.19.1

External links

http://github.com/krb5/krb5/releases
http://web.mit.edu/kerberos/advisories/
http://github.com/krb5/krb5/commit/fc98f520caefff2e5ee9a0026fdf5109944b3562

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.