SB2021051122 - Multiple vulnerabilities in Microsoft Skype for Business and Lync

Description

This security bulletin contains information about 2 vulnerabilities.

1) Code Injection (CVE-ID: CVE-2021-26422)

CWE-ID: CWE-94 - Improper Control of Generation of Code ('Code Injection')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote user to execute arbitrary code on the target system.

The vulnerability exists due to improper input validation in Skype for Business and Lync. A remote administrator can execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

2) Spoofing attack (CVE-ID: CVE-2021-26421)

CWE-ID: CWE-451 - User Interface (UI) Misrepresentation of Critical Information (Clickjacking, spoofing)

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to perform spoofing attack.

The vulnerability exists due to incorrect processing of user-supplied data in Skype for Business and Lync. A remote authenticated attacker can spoof page content.

Remediation

Install update from vendor's website.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26422
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26421