Vulnerability identifier: #VU57324

Vulnerability risk: Medium

CVSSv3.1: 5 [CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

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: 4.14.0 - 4.14.7, 4.13.0 - 4.13.11

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External links
http://bugzilla.samba.org/show_bug.cgi?id=14770
http://bugzilla.redhat.com/show_bug.cgi?id=2013080
http://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.