Security Updates for Microsoft Skype for Business (May 2021)

high Nessus Plugin ID 149479
New! Plugin Severity Now Using CVSS v3

The calculated severity for Plugins has been updated to use CVSS v3 by default. Plugins that do not have a CVSS v3 score will fall back to CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.

Synopsis

The Microsoft Skype for Business installation on the remote host is affected by multiple vulnerabilities.

Description

The Microsoft Skype for Business installation on the remote host is missing security updates. It is, therefore, affected by multiple vulnerabilities:

- A session spoofing vulnerability exists. An attacker can exploit this to perform actions with the privileges of another user. (CVE-2021-26421)

- A remote code execution vulnerability. An attacker can exploit this to bypass authentication and execute unauthorized arbitrary commands. (CVE-2021-26422)

Solution

Microsoft has released KB5003729 to address this issue.

See Also

http://www.nessus.org/u?5d97ea49

Plugin Details

Severity: High

ID: 149479

File Name: smb_nt_ms21_may_skype.nasl

Version: 1.3

Type: local

Agent: windows

Published: 5/14/2021

Updated: 5/18/2021

Dependencies: office_installed.nasl, microsoft_lync_server_installed.nasl, smb_hotfixes.nasl, ms_bulletin_checks_possible.nasl

Risk Information

CVSS Score Source: CVE-2021-26422

VPR

Risk Factor: Medium

Score: 5.9

CVSS v2

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 4.8

Vector: AV:N/AC:L/Au:S/C:P/I:P/A:P

Temporal Vector: E:U/RL:OF/RC:C

CVSS v3

Risk Factor: High

Base Score: 7.2

Temporal Score: 6.3

Vector: CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:microsoft:skype_for_business

Required KB Items: SMB/MS_Bulletin_Checks/Possible

Exploit Ease: No known exploits are available

Patch Publication Date: 5/13/2021

Vulnerability Publication Date: 5/13/2021

Reference Information

CVE: CVE-2021-26421, CVE-2021-26422

MSKB: 5003729

MSFT: MS21-5003729

IAVA: 2021-A-0217