CVE-2020-8187: 
Citrix ADC VPX vulnerability analysis and mitigation

Citrix ADC and Citrix Gateway versions before 11.1-63.9 and 12.0-62.10 were affected by an improper input validation vulnerability identified as CVE-2020-8187. The vulnerability was discovered in early 2020 and officially disclosed on July 7, 2020. This security flaw specifically affects systems with configured SSL VPN or AAA endpoints (Citrix Blog).

The vulnerability stems from improper input validation in the affected Citrix products. It specifically affects systems running Citrix ADC and Citrix Gateway versions 12.0 and 11.1. The vulnerability is particularly concerning as it can be exploited by unauthenticated remote users, requiring only a configured SSL VPN or AAA endpoint to be present (CVE Mitre).

When successfully exploited, CVE-2020-8187 allows unauthenticated users to perform a denial of service attack against the affected systems. The impact is specifically limited to environments where Gateway or authentication virtual servers are being used, while other virtual servers such as load balancing and content switching are not affected (Citrix Blog).

The vulnerability requires no authentication to exploit, making it particularly dangerous. However, Citrix has stated that at the time of disclosure, they were not aware of any active exploitation of this vulnerability in the wild (Citrix Blog).

Citrix released patches to address this vulnerability in versions 11.1-63.9 and 12.0-62.10. The company strongly recommended quick application of the supplied patches to mitigate the risk. Organizations can use Citrix ADM Service for simplified and bulk upgrade of all their Citrix ADC instances (Citrix Blog).