Eclipse BIRT - RCE (CVE-2021-34427)

CVE-2021-34427 is a critical vulnerability in Eclipse BIRT versions 4.8.0 and earlier that allows remote attackers to inject malicious JSP code by manipulating query parameters. Exploiting this flaw could enable attackers to execute arbitrary code on the server, potentially leading to full system compromise and unauthorized access to sensitive data.

CrowdSec has been tracking this vulnerability and its exploits since 10th of December 2025.

Insights from the CrowdSec network reveal that the attackers trying to exploit CVE-2021-34427 are composed of a fairly even mix of opportunistic and targeted actors. Some attackers employ preliminary reconnaissance, while others use indiscriminate scanning. Telemetry from the CrowdSec network also shows that exploitation activity for CVE-2021-34427 remains steady week-over-week. Attack volumes are consistent with long-term trends, indicating sustained interest from threat actors. CVE-2021-34427 continues to be an active part of the threat landscape and will likely remain this way for the forseeable future.

Attackers exploit this vulnerability by sending crafted requests to the /document endpoint with malicious query parameters, resulting in the creation and execution of attacker-controlled JSP files within the application directory. Subsequent requests to the uploaded .jsp files are used to execute arbitrary code on the server.