ManageEngine OpManager - RCE (CVE-2020-28653)

CVE-2020-28653 is a critical remote code execution vulnerability in Zoho ManageEngine OpManager versions prior to Stable build 125203 and Released build 125233, exploitable via the Smart Update Manager (SUM) servlet. Attackers can leverage this flaw to execute arbitrary code on the affected server without authentication, potentially leading to full system compromise.

CrowdSec has been tracking this vulnerability and its exploits since 15th of October 2025.

Based on data from the CrowdSec network, nearly all observed exploitation of CVE-2020-28653 is fully opportunistic, with attackers indiscriminately scanning the entire internet. These attacks are automated and lack any form of target selection or reconnaissance. Data from the CrowdSec community also indicates a gradual decrease in attacks targeting CVE-2020-28653. While still present in the wild, exploitation levels have dropped noticeably week-over-week. This may signal that the vulnerability is becoming less relevant or that defenses are improving fast enough for attackers to lose interest.

Attackers exploit the vulnerable SUM servlets by sending crafted POST requests to endpoints such as /servlets/com.adventnet.tools.sum.transport.SUMCommunicationServlet and /servlets/com.adventnet.tools.sum.transport.SUMHandShakeServlet to trigger Java deserialization and achieve remote code execution.