Cisco has addressed a critical severity remote code execution flaw, tracked as CVE-2020-3495, that affects multiple versions of Cisco Jabber for Windows. Cisco Jabber for Windows is a desktop collaboration client that integrates users with presence, audion, video and web conferencing, instant messaging (IM), cloud messaging, and desktop sharing. The CVE-2020-3495 flaw is caused by the improper input validation of incoming messages’ contents, it could be exploited by an authenticated, remote attacker to execute arbitrary code with the privileges of the user account that is running the Cisco Jabber client software. An authenticated, remote attacker can exploit the flaw by sending specially-crafted Extensible Messaging and Presence Protocol (XMPP) messages to vulnerable devices. The CVE-2020-3495 flaw can be also exploited when the Jabber for Windows client is running in the background, in any case no user interaction is required to trigger the issue.
Systems using Cisco Jabber in phone-only mode without XMPP messaging services enabled are not vulnerable to attacks exploiting this issue. Cisco also added that the vulnerability is not exploitable when Cisco Jabber is configured to use messaging services other than XMPP messaging. The vulnerability is wormable and its exploitation could be automated.
Remote Code Execution
Windows Cisco Jabber client (12.1 to 12.9).
Update to a patched version.