CVE-2021-1536: 
Cisco Webex Teams vulnerability analysis and mitigation

A vulnerability (CVE-2021-1536) was discovered in multiple Cisco Webex products including Webex Meetings Desktop App for Windows, Webex Meetings Server, Webex Network Recording Player for Windows, and Webex Teams for Windows. The vulnerability was disclosed on June 2, 2021, and allows an authenticated, local attacker with valid Windows system credentials to perform a DLL injection attack on affected devices (Cisco Advisory).

The vulnerability stems from incorrect handling of directory paths at runtime, classified as CWE-427 (Uncontrolled Search Path Element). The CVSS v3.1 scores vary between sources, with NVD rating it as 7.8 HIGH (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) while Cisco assessed it as 4.8 MEDIUM (CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L) (NVD).

A successful exploitation could allow an attacker to execute arbitrary code on the affected system with the privileges of another user account. The attacker could exploit this vulnerability by inserting a configuration file in a specific path in the system, which can cause a malicious DLL file to be loaded when the application starts (Cisco Advisory).

To exploit this vulnerability, an attacker must first have valid credentials on the Windows system and local access to the affected device. At the time of disclosure, Cisco PSIRT was not aware of any public announcements or malicious use of this vulnerability (Cisco Advisory).

Cisco has released software updates to address this vulnerability. The fixed versions include Webex Meetings Desktop App for Windows 41.1.5.1141.2.9.23, Webex Meetings Server 3.0 MR4/4.0 MR4, Webex Network Recording Player for Windows 41.1.5.1141.2.9.23, and Webex Teams for Windows versions 41.3.0.18986/41.4.0.18737/41.5.0.18815. No workarounds are available for this vulnerability (Cisco Advisory).