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Vulnerability record · CVE-2020-21523 · published 30 September 2020

CVE-2020-21523: Halo injection vulnerability

Halo · Halo

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")}

9.8 CVSS 3.1 Critical EPSS 2.6% · top 15.3% CWE-74 · Injection
9.8CVSS 3.1 base score, v2 10.0
2.6%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 2 tagged exploit
17 Jun 2026Last modified by NVD

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")}

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/halo-dev/halo/issues/419 ExploitIssue TrackingThird Party Advisory
https://github.com/halo-dev/halo/issues/419 ExploitIssue TrackingThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2022-32994Halo unrestricted file upload vulnerabilityHalo CMS v1.5.3 was discovered to contain an arbitrary file upload vulnerability via the component /api/admin/attachments/upload.EPSS 19%9.8CVE-2022-32995Halo server-side request forgery (ssrf) vulnerabilityHalo CMS v1.5.3 was discovered to contain a Server-Side Request Forgery (SSRF) via the template remote download function.EPSS 18%9.8CVE-2020-18980Halo vulnerabilityRemote Code Executon vulnerability in Halo 0.4.3 via the remoteAddr and themeName parameters.EPSS 1.5%9.8CVE-2020-21526Halo path traversal vulnerabilityAn Arbitrary file writing vulnerability in halo v1.1.3. In an interface to write files in the background, a directory traversal check is performed on…EPSS 1.9%9.8CVE-2020-21522Halo path traversal vulnerabilityAn issue was discovered in halo V1.1.3. A Zip Slip Directory Traversal Vulnerability in the backend,the attacker can overwrite some files, such as ft…EPSS 1.5%9.1CVE-2025-44594Halo server-side request forgery (ssrf) vulnerabilityhalo v2.20.17 and before is vulnerable to server-side request forgery (SSRF) in /apis/uc.api.storage.halo.run/v1alpha1/attachments/-/upload-from-url.EPSS 0.37%9.1CVE-2020-19038Halo missing authorization vulnerabilityFile Deletion vulnerability in Halo 0.4.3 via delBackup.EPSS 1.2%9.1CVE-2020-21524Halo xml external entity (xxe) vulnerabilityThere is a XML external entity (XXE) vulnerability in halo v1.1.3, The function of importing other blogs in the background(/api/admin/migrations/word…EPSS 1.5%

Source: NIST National Vulnerability Database (record CVE-2020-21523), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.