CVE intelligence and bounded remediation

CVE-2020-27387 — Horizontcms Project Horizontcms security vulnerability

High CVSS 8.8

An unrestricted file upload issue in HorizontCMS through 1.0.0-beta allows an authenticated remote attacker (with access to the FileManager) to upload and execute arbitrary PHP code by uploading a PHP payload, and then using the FileManager's rename function to provide the payload (which will receive a random name on the server) with the PHP extension, and finally executing the PHP file via an HTTP GET request to /storage/<php_file_name>. NOTE: the vendor has patched this while leaving the version number at 1.0.0-beta.

Severity
High
CVSS
8.8 (3.1)
Published
2020-11-05
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-434

Affected products

  • horizontcms_project / horizontcms / 1.0.0

Showing 1 representative product identities from 9 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Path traversal, unsafe upload, and file handling

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Check exposure

  • Trace untrusted filenames, archive entries, URLs, and path segments into read, write, include, extraction, and upload operations.
  • Identify filesystem roots, mount permissions, symbolic-link behavior, archive handling, and whether uploaded content is web-accessible or executable.
  • Review canonicalization and containment checks across supported operating systems and storage backends.

Remediate safely

  • Generate server-side storage identifiers and resolve paths beneath a fixed root using filesystem-aware containment checks.
  • Reject absolute, parent-relative, alternate-separator, device, link, and archive entries that escape the intended root.
  • Store uploads outside executable or served paths, validate type and size, and use private atomic temporary files.

Authoritative sources

Complete CVE record and remediation plan

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