Lucee Admin - RCE (CVE-2021-21307)
537Exploiting 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. Data from the CrowdSec community also indicates a gradual decrease in attacks targeting CVE-2021-21307. 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.
Observed exploitation attempts involve requests to URLs containing /lucee/admin/imgprocess.cfm.
Exploitation
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Protection
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Blocklist
With our advanced worldwide network detection, CrowdSec can provide a list of IPs known for exploiting the vulnerability.
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