Temenos products might be affected by Log4j vulnerability as there has been articles in Temenos baseCamp site where Log4j is being used and Temenos themselves has issued an advisory for both OnPremise as well as Cloud customers over here. In addition to that there has been blog post from Temenos on the products that were affected by Log4j vulnerability
Temenos Journey Manager known as TJM is affected by Log4j vulnerability as all of them using log4j version v 2.14.x. It seems Temenos did try to exploit the vulnerability in TJM but so far their efforts were not successful. Inspite of that Temenos has decided to apply a mitigation so that Temenos products are not affected. On Sunday Dec12th, the patch was applied to all the TJM instances in AWS, Azure and Private Cloud
For VDC and VDC+ customers, it seems this patch is not needed as they have outbound traffic controls to specific ports requested by clients.You can see more about it in the below link
Source: https://journey.temenos.com/index.php/read/announcements/temenos-journey-manager-log4j-vulnerability