CVE-2026-114622
Deferred Deferred - Pending Action

Path Traversal in baserCMS via BcThemeFile Plugin

Vulnerability report for CVE-2026-114622, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-10-23

Last updated on: 2026-10-23

Assigner: GitHub, Inc.

Description

baserCMS is a website development framework. In versions 5.2.3 before 5.3.2 and 5.4.0 before 5.4.2, the optional BcThemeFile plugin's Admin API validates a raw path in ThemeFilesService::update() and getFullpath(), but ThemeFileForm::_execute() subsequently applies rawurldecode() to fullpath before writing. Because normalizePath() resolves only literal dot segments, percent-encoded traversal can pass the containment checks and become a path outside the theme directory at the write sink. An authenticated administrator can write PHP files into writable locations such as webroot and execute them, exceeding the intended theme-template editing boundary. The source also identifies the same check-before-decode ordering in ThemeFilesService::copy(), although that path was not dynamically verified. Exploitation requires the non-default plugin, an administrator session, and a same-origin Origin header; USE_CORE_ADMIN_API=false does not block session-authenticated requests. The Admin web form is not affected by this encoded-path tampering because FormProtection protects fullpath. This is a third bypass of the protections associated with CVE-2026-30940, using encoded traversal decoded after validation. This issue has been patched in versions 5.3.2 and 5.4.2.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-10-23
Last Modified
2026-10-23
Generated
2026-10-23
AI Q&A
2026-10-23
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
baserproject basercms >= 5.2.3, < 5.3.2
baserproject basercms >= 5.4.0, < 5.4.2

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-180 The product validates input before it is canonicalized, which prevents the product from detecting data that becomes invalid after the canonicalization step.
CWE-22 The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This vulnerability affects baserCMS versions 5.2.3 before 5.3.2 and 5.4.0 before 5.4.2. It involves the BcThemeFile plugin's Admin API, where path validation occurs before URL decoding. An attacker can exploit percent-encoded path traversal to bypass containment checks and write PHP files outside the intended theme directory, leading to remote code execution.

Detection Guidance

Check if the BcThemeFile plugin is installed and enabled. Inspect web server logs for unusual file write operations or PHP file uploads in theme directories. Verify if normalizePath() and rawurldecode() are used in ThemeFilesService and ThemeFileForm classes.

Impact Analysis

An authenticated administrator with access to the vulnerable plugin can upload and execute malicious PHP files on the server. This could lead to full system compromise, data theft, or unauthorized access to sensitive information. Exploitation requires an active administrator session and a same-origin Origin header.

Compliance Impact

This vulnerability could lead to unauthorized data access or modification, violating GDPR's integrity and confidentiality principles or HIPAA's security requirements. Organizations using affected baserCMS versions may face compliance violations, legal penalties, and reputational damage if exploited.

Mitigation Strategies

Upgrade baserCMS to version 5.3.2 or 5.4.2 or later. Disable the BcThemeFile plugin if not needed. Restrict administrator access and enforce strict file write permissions. Monitor for unauthorized PHP file uploads in webroot directories.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-114622. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart