CVE-2020-21523
CVSS v3
9.8
CRITICAL
EPSS Score
2.6 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
A Server-Side Freemarker template injection vulnerability in halo CMS v1.1.3 In the Edit Theme File function. The ftl file can be edited. This is the Freemarker template file. This file can cause arbitrary code execution when it is rendered in the background. exp: <#assign test="freemarker.template.utility.Execute"?new()> ${test("touch /tmp/freemarkerPwned")}
Technical details
- Published
- 2020-09-30
Frequently asked questions
What is CVE-2020-21523?
A Server-Side Freemarker template injection vulnerability in halo CMS v1.1.3 In the Edit Theme File function. The ftl file can be edited. This is the Freemarker template file. This file can cause arbitrary code execution when it is rendered in the background. exp: <#assign test="freemarker.template.utility.Execute"?new()> ${test("touch /tmp/freemarkerPwned")}
Is CVE-2020-21523 actively exploited?
Active exploitation of CVE-2020-21523 has not been confirmed. Its EPSS score was 2.6% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2020-21523?
CVE-2020-21523 has a CVSS v3 base score of 9.8 (CRITICAL severity).
Is CVE-2020-21523 affecting your environment?
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