CVE-2026-25237
📋 TL;DR
This vulnerability in PEAR (PHP Extension and Application Repository) allows remote code execution when attacker-controlled content reaches the preg_replace() function with the /e modifier in bug update email handling. It affects all PEAR installations prior to version 1.33.0. Attackers could execute arbitrary PHP code on vulnerable systems.
💻 Affected Systems
- PEAR (PHP Extension and Application Repository)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full server compromise allowing attackers to execute arbitrary PHP code, access sensitive data, install backdoors, or pivot to other systems.
Likely Case
Remote code execution leading to web shell installation, data exfiltration, or service disruption.
If Mitigated
Limited impact if proper input validation and output encoding are implemented, though the core vulnerability remains.
🎯 Exploit Status
The vulnerability is in a widely used PHP component and exploitation is straightforward once the attack vector is identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.33.0
Vendor Advisory: https://github.com/pear/pearweb/security/advisories/GHSA-vhw6-hqh9-8r23
Restart Required: No
Instructions:
1. Update PEAR to version 1.33.0 or later using: pear upgrade pear
2. Verify the update completed successfully
3. Test functionality to ensure no breaking changes
🔧 Temporary Workarounds
Disable bug update email functionality
allTemporarily disable the vulnerable bug update email handling feature if not required
# Modify PEAR configuration to disable bug update emails
# Check pearweb configuration files for email-related settings
Input validation and sanitization
allImplement strict input validation and output encoding for any content that reaches the vulnerable function
# Add input validation in PHP code:
# filter_var($input, FILTER_SANITIZE_STRING);
# htmlspecialchars($input, ENT_QUOTES, 'UTF-8');
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to block suspicious patterns in email handling requests
- Restrict network access to systems using vulnerable PEAR versions and monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check PEAR version with: pear version | grep 'PEAR Version'Check Version:
pear version | grep 'PEAR Version'Verify Fix Applied:
Verify version is 1.33.0 or higher: pear version | grep 'PEAR Version'📡 Detection & Monitoring
Log Indicators:
- Unusual PHP error logs related to preg_replace() with /e modifier
- Suspicious POST requests to bug update email endpoints
- Unexpected PHP code execution in web server logs
Network Indicators:
- Unusual outbound connections from web server after bug update requests
- Traffic patterns indicating web shell communication
SIEM Query:
source="web_logs" AND ("preg_replace" OR "/e modifier" OR "bug update") AND status=200