# CVE-2021-21307: Lucee Admin - RCE

> Live exploitation tracking for CVE-2021-21307 by the CrowdSec Live Exploit Tracker, built from real-world attack data crowdsourced from CrowdSec's global network.

Page: https://tracker.crowdsec.net/cves/CVE-2021-21307

## Key facts

- **Exploitation phase:** Background Noise. Continuous low-level scanning or exploitation attempts are observed, mostly opportunistic and automated.
- **CVSS score:** 8.6
- **Public exploit available:** Yes
- **Affected products:** Lucee
- **Weaknesses:** CWE-862 (Missing Authorization)
- **Tags:** web_application

## Description

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](https://euvd.enisa.europa.eu/vulnerability/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 15th of May 2024.

According to CrowdSec data, while opportunistic exploitation dominates, a portion of threat actors trying to exploit CVE-2021-21307 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-2021-21307 remains steady week-over-week. Attack volumes are consistent with long-term trends, indicating sustained interest from threat actors. CVE-2021-21307 continues to be an active part of the threat landscape and will likely remain this way for the forseeable future.

Observed exploitation attempts involve requests to URLs containing `/lucee/admin/imgprocess.cfm`.

## Timeline

- 2021-02-11: CVE Published. CVE-2021-21307 is published to NVD.
- 2024-05-15: Rule Released. CrowdSec releases a rule to detect CVE-2021-21307 exploitation attempts against the CrowdSec Network.
- 2024-05-15: CrowdSec First Seen. CrowdSec observes in-the-wild exploitation of CVE-2021-21307 for the first time.

## References

- https://github.com/lucee/Lucee/security/advisories/GHSA-2xvv-723c-8p7r
- https://github.com/lucee/Lucee/commit/6208ab7c44c61d26c79e0b0af10382899f57e1ca
- https://github.com/httpvoid/writeups/blob/main/Apple-RCE.md
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-21307.yaml

## Live exploitation data

The [Live Exploit Tracker page](https://tracker.crowdsec.net/cves/CVE-2021-21307) follows observed exploitation activity for CVE-2021-21307. [Request an API key](https://tracker.crowdsec.net/request-api-key) for full access to its exploitation timeline, attacking IP addresses and blocklists.