CVE-2026-40187: EGroupware Authenticated RCE via Malicious eTemplate Upload
Summary
CVE-2026-40187: EGroupware has Authenticated RCE via Malicious eTemplate Upload. Affects egroupware/egroupware across 2 version ranges.
< 23.1.20260601
>= 26.0.20251208, < 26.4.20260413
Fixed in 23.1.20260601 or 26.4.20260413, depending on the release line you run. How to fix ↓
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Background
EGroupware is an open-source groupware application that provides tools for collaboration, project management, and communication. It allows users to manage tasks, calendars, and files in a shared environment. However, a critical vulnerability has been identified that allows authenticated administrators to execute arbitrary OS commands through the upload of malicious eTemplate XML files.
Vulnerability Detail
The vulnerability arises from the Widget::expand_name() method in the api/src/Etemplate/Widget.php file, which uses PHP's eval() function to process template widget attribute values. The method only escapes double quotes, leaving backtick characters unescaped. This oversight allows an attacker with admin privileges to inject shell commands into the eval string, leading to Remote Code Execution (RCE) on the server. This vulnerability can be exploited by uploading a crafted eTemplate file that contains backticks, enabling the execution of arbitrary commands as the web server user.
How To Fix
Fixed versions by release line
The minimum fixed version depends on the release line you run.
-
< 23.1.2026060123.1.20260601composer require egroupware/egroupware:23.1.20260601 -
>= 26.0.20251208, < 26.4.2026041326.4.20260413composer require egroupware/egroupware:26.4.20260413
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Workaround
If immediate patching is not possible, consider applying the following workaround: Set the disable_functions directive in your php.ini file to include exec,passthru,shell_exec,system,proc_open,popen. This will block the execution of shell commands through backticks in PHP, mitigating the risk of exploitation.
Conclusion
The CVE-2026-40187 vulnerability in EGroupware allows authenticated administrators to execute arbitrary OS commands through the upload of malicious eTemplate files. It is crucial for users to update to the latest patched versions or apply the recommended workarounds to mitigate the risk of exploitation.
See every vulnerability recorded for egroupware/egroupware →
FAQ
The CVSS score of this vulnerability is 8.6, indicating a high severity level.
Any EGroupware installation where an admin account is compromised or a malicious admin exists, and the server is not configured with disable_functions blocking shell execution.
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An attacker can escalate from web application access to arbitrary OS command execution, potentially allowing them to read sensitive configuration files and pivot to other services.
No, the official Docker deployment is not affected due to the disable_functions setting in php.ini, which blocks shell execution.
References
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