CVE-2021-21307: Lucee Server is a dynamic, Java based (JSR-223), tag and scripting language used for rapid web application dev

This week

HIGH 8.6REMOTEUPGRADE

CVE-2021-21307 is a high-severity flaw (CVSS 8.6) affecting lucee server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
EPSS top 1%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	89.2% (top 1%)
CISA exploited list	No
Weakness	CWE-862
Published	2021-02-11
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: lucee

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-02-11 19:15 UTCPublished CVE record published
2026-06-17 03:35 UTCUpdated Record last modified

lucee lucee server UPGRADE

Affected: >= 5.3.5.00 and < 5.3.5.96 · >= 5.3.6.00 and < 5.3.6.68 · >= 5.3.7.00 and < 5.3.7.47

Fixed in: 5.3.5.96, 5.3.6.68, 5.3.7.47

Safe to downgrade to: a release before 5.3.5.00

1. Check installed version

apt-cache policy lucee-server || rpm -q lucee-server || lucee-server --version

2. UPGRADE to 5.3.5.96 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade lucee-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade lucee-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 5.3.5.00 (Debian / Ubuntu)

apt-cache madison lucee-server sudo apt install lucee-server=<VERSION_BEFORE_5.3.5.00> sudo apt-mark hold lucee-server

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list lucee-server sudo dnf downgrade lucee-server-<VERSION_BEFORE_5.3.5.00> sudo dnf versionlock add lucee-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Metasploit: Lucee Administrator imgProcess.cfm Arbitrary File Write
Nuclei scan template: Lucee Admin - Remote Code Execution

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-21307?

lucee server: upgrade to 5.3.5.96, 5.3.6.68, 5.3.7.47. Exact commands for each OS are on this page.

Is CVE-2021-21307 being exploited?

CVE-2021-21307 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-21307 affect?

CVE-2021-21307 affects lucee server. Severity is high (CVSS 8.6). 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 f

How urgent is CVE-2021-21307?

Priority 65/100. High severity; EPSS top 1%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Java vulnerabilities

References

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