#VU57324 NULL pointer dereference in Samba - CVE-2021-3671

Vulnerability identifier: #VU57324

Vulnerability risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-3671

CWE-ID: CWE-476

Exploitation vector: Local network

Exploit availability: No

Vulnerable software:
Samba
Server applications / Directory software, identity management

Vendor: Samba

Description

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

The vulnerability exists due to a NULL pointer dereference error in the way samba kerberos server handles missing sname attribute in TGS-REQ (Ticket Granting Server - Request). A remote authenticated user can send a specially crafted request to the samba server and perform a denial of service (DoS) attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Samba: 4.13.0 - 4.14.7

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External links
https://bugzilla.samba.org/show_bug.cgi?id=14770
https://bugzilla.redhat.com/show_bug.cgi?id=2013080
https://github.com/heimdal/heimdal/commit/04171147948d0a3636bc6374181926f0fb2ec83a

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the local network (LAN).

Is there known malware, which exploits this vulnerability?

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