Multiple vulnerabilities in Microsoft Skype for Business and Lync

Published: 2021-02-09

Risk	Medium
Patch available	YES
Number of vulnerabilities	2
CVE-ID	CVE-2021-24073 CVE-2021-24099
CWE-ID	CWE-451 CWE-20
Exploitation vector	Network
Public exploit	N/A
Vulnerable software	Skype for Business Server Server applications / Conferencing, Collaboration and VoIP solutions Microsoft Lync Client/Desktop applications / Messaging software
Vendor	Microsoft

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Spoofing attack

EUVDB-ID: #VU50486

Risk: Low

CVSSv4.0: 0.1 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-24073

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

Exploit availability: No

Description

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.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Skype for Business Server: 2015 CU8

Microsoft Lync: 2013

CPE2.3

External links

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-24073

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

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

2) Input validation error

EUVDB-ID: #VU50487

Risk: Medium

CVSSv4.0: 4.9 [CVSS:4.0/AV:N/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-2021-24099

CWE-ID: CWE-20 - Improper input validation