Executive Summary

CVE-2026-25237 is a critical vulnerability in the PEAR framework, specifically in the pearweb project versions prior to 1.33.0. It occurs in the mail_bug_updates() function, which uses the preg_replace() function with the deprecated /e modifier. This modifier causes the replacement string to be evaluated as PHP code. If an attacker can control the input processed by this function, such as bug comments, they can inject and execute arbitrary PHP code remotely.

This vulnerability is classified under CWE-624, meaning the regular expression used either contains an executable component influenced by user input or allows execution through pattern modifiers, leading to potential remote code execution.

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Impact Analysis

This vulnerability can allow an attacker to execute arbitrary PHP code on the affected system remotely. This can lead to full system compromise, unauthorized access, data theft, or disruption of services. Because the attacker can run code with the privileges of the web server, it poses a severe security risk.

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability arises from the use of the preg_replace() function with the deprecated /e modifier in the mail_bug_updates() function within pearweb versions prior to 1.33.0. To detect if your system is vulnerable, you should check the version of pearweb installed and inspect the source code for the presence of preg_replace() calls using the /e modifier, especially in the file public_html/bugs/include/functions.inc.'}, {'type': 'paragraph', 'content': 'A practical approach is to run commands that identify the pearweb version and search for the vulnerable code pattern. For example:'}, {'type': 'list_item', 'content': 'Check pearweb version: `pear version` or check the installed package version via your package manager.'}, {'type': 'list_item', 'content': 'Search for preg_replace with /e modifier in source code: `grep -r "preg_replace.*\\/e" /path/to/pearweb/`'}, {'type': 'list_item', 'content': 'Specifically check the vulnerable file: `grep "preg_replace" /path/to/pearweb/public_html/bugs/include/functions.inc`'}, {'type': 'paragraph', 'content': 'If these commands reveal usage of preg_replace with the /e modifier, your system is likely vulnerable.'}] [1]

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Mitigation Strategies

The primary mitigation step is to upgrade pearweb to version 1.33.0 or later, where this vulnerability has been patched.

If upgrading immediately is not possible, consider applying temporary code fixes by removing or replacing the use of preg_replace() with the /e modifier in the mail_bug_updates() function to prevent PHP code execution.

Additionally, restrict access to the affected functionality and monitor for suspicious inputs or activity that could exploit this vulnerability.

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Compliance Impact

The vulnerability allows remote PHP code execution through attacker-controlled input, which can lead to unauthorized access or manipulation of data handled by the affected system.

Such unauthorized code execution risks compromising the confidentiality, integrity, and availability of data, potentially violating requirements in common standards and regulations like GDPR and HIPAA that mandate protection of personal and sensitive information.

Therefore, if exploited, this vulnerability could negatively impact compliance by exposing sensitive data or enabling unauthorized system control.

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