Lucee Admin - RCE (CVE-2021-21307)
661Exploiting IPs reported
Lucee Server is a dynamic, Java based (JSR-223), tag and scripting language used for rapid web application development. In Lucee Admin before versions 5.3.7.47, 5.3.6.68 or 5.3.5.96 there is an unauthenticated remote code exploit. This is fixed in versions 5.3.7.47, 5.3.6.68 or 5.3.5.96. As a workaround, one can block access to the Lucee Administrator.
CrowdSec analysis
CVE-2021-21307 is a vulnerability in Lucee Server that allows unauthenticated remote code execution through insufficient access controls in the administrative image processing component.
CrowdSec has been tracking this vulnerability and its exploits since 10th of March 2025.
CrowdSec network data shows that most actors exploiting CVE-2021-21307 rely on broad, untargeted scans with minimal filtering. The activity is largely automated and opportunistic in nature. CrowdSec data also reveals a clear uptick in attacks involving CVE-2021-21307 over the past week. Activity is above the usual baseline, suggesting growing attention from attackers. This may reflect rising awareness, recent exploit releases, or expanded targeting efforts.
Observed exploitation attempts involve requests to URLs containing /lucee/admin/imgprocess.cfm.
Exploitation
Get real-time information about exploitation attempts and actors involved.
Protection
Find out relevant information to protect your stack against this CVE.
Blocklist
With our advanced worldwide network detection, CrowdSec can provide a list of IPs known for exploiting the vulnerability.
To increase your protection against this CVE, block exploitation attempts with this list of identified actors.