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CVE-2021-21307

89
FAUCET Score

CVE-2021-21307 is an unauthenticated remote code execution (RCE) vulnerability affecting Lucee Server versions prior to 5.3.7.47, 5.3.6.68, or 5.3.5.96. This critical flaw, with a CVSS score of 9.8, allows attackers to execute arbitrary code without authentication, leading to complete compromise of confidentiality, integrity, and availability. Exploit code is publicly available via Metasploit modules and Nuclei templates, and the vulnerability has garnered significant community discussion, indicating high awareness and potential for exploitation. While not currently on CISA's KEV catalog, its high EPSS score and FAUCET Risk Score of 100/100 suggest a high likelihood of future exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
>= 5.3.5.00, < 5.3.5.96CPE matchmatch criteria
cpe:2.3:a:lucee:lucee_server:*:*:*:*:*:*:*:*
>= 5.3.6.00, < 5.3.6.68CPE matchmatch criteria
cpe:2.3:a:lucee:lucee_server:*:*:*:*:*:*:*:*
>= 5.3.7.00, < 5.3.7.47CPE matchmatch criteria
cpe:2.3:a:lucee:lucee_server:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.6HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
4.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
89.19%
Probability of exploitation in next 30 days
EPSS Percentile
99.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
Metasploit: Lucee Administrator imgProcess.cfm Arbitrary File Write · Jan 15, 2021
Nuclei: CVE-2021-21307 · Jul 18, 2021
This CVE's current EPSS score of 0.8919 is in the 99th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

ciacfug.org / blog/updating-lucee-as-part-of-a-vulnerability-alert-response
PatchThird Party Advisory
packetstormsecurity.com / files/163864/Lucee-Administrator-imgProcess.cfm-Arbitrary-File-Write.html
ExploitThird Party AdvisoryVDB Entry
dev.lucee.org / t/lucee-vulnerability-alert-november-2020/7643
Vendor Advisory
github.com / httpvoid/writeups/blob/main/Apple-RCE.md
ExploitThird Party Advisory
github.com / lucee/Lucee/commit/6208ab7c44c61d26c79e0b0af10382899f57e1ca
PatchThird Party Advisory
github.com / lucee/Lucee/security/advisories/GHSA-2xvv-723c-8p7r
Product
portswigger.net / daily-swig/security-researchers-earn-50k-after-exposing-critical-flaw-in-apple-travel-portal
Press/Media CoverageThird Party Advisory