DrayTek VigorConnect - LFI (CVE-2021-20123)

CVE-2021-20123 is a vulnerability in DrayTek VigorConnect that allows unauthenticated attackers to exploit a local file inclusion flaw, enabling the download of arbitrary files from the underlying operating system with root-level access.

CrowdSec has been tracking this vulnerability and its exploits since 24th of September 2024.

According to CrowdSec data, while opportunistic exploitation dominates, a portion of threat actors trying to exploit CVE-2021-20123 apply basic targeting methods such as port or service detection. This indicates emerging patterns of selective targeting. Telemetry from the CrowdSec network also shows that exploitation activity for CVE-2021-20123 remains steady week-over-week. Attack volumes are consistent with long-term trends, indicating sustained interest from threat actors. CVE-2021-20123 continues to be an active part of the threat landscape and will likely remain this way for the forseeable future.

Attack attempts are typically directed at URLs containing acsserver/downloadfileservlet.