CVE-2023-0568
📋 TL;DR
A buffer overflow vulnerability in PHP's path resolution function allows writing a null byte beyond allocated memory when processing paths near system MAXPATHLEN limits. This could lead to memory corruption potentially enabling unauthorized data access or modification. Affects PHP 8.0.X before 8.0.28, 8.1.X before 8.1.16, and 8.2.X before 8.2.3.
💻 Affected Systems
- PHP
📦 What is this software?
Php by Php
Php by Php
Php by Php
⚠️ Risk & Real-World Impact
Worst Case
Memory corruption leading to arbitrary code execution, privilege escalation, or sensitive data disclosure.
Likely Case
Application crashes, denial of service, or limited memory corruption affecting adjacent data structures.
If Mitigated
Minimal impact if path lengths are controlled or systems are patched.
🎯 Exploit Status
Exploitation requires precise path length conditions and memory layout knowledge.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: PHP 8.0.28, PHP 8.1.16, PHP 8.2.3
Vendor Advisory: https://bugs.php.net/bug.php?id=81746
Restart Required: Yes
Instructions:
1. Identify PHP version with 'php -v'. 2. Update PHP using package manager: 'apt update && apt upgrade php' (Debian/Ubuntu) or 'yum update php' (RHEL/CentOS). 3. Restart web server: 'systemctl restart apache2' or 'systemctl restart nginx'. 4. Verify update with 'php -v'.
🔧 Temporary Workarounds
Path Length Restriction
allImplement input validation to reject paths approaching MAXPATHLEN limits.
Web Server Configuration
linuxConfigure web server to limit maximum request/URL length to prevent triggering conditions.
Apache: LimitRequestLine 4094
Nginx: client_max_body_size 1m; large_client_header_buffers 4 8k;
🧯 If You Can't Patch
- Implement strict input validation for all path inputs to ensure they don't approach MAXPATHLEN limits.
- Deploy WAF rules to block requests with unusually long paths or URL parameters.
🔍 How to Verify
Check if Vulnerable:
Run 'php -v' and check if version is in affected range: 8.0.0-8.0.27, 8.1.0-8.1.15, or 8.2.0-8.2.2.Check Version:
php -v | head -1Verify Fix Applied:
Run 'php -v' and confirm version is 8.0.28+, 8.1.16+, or 8.2.3+.📡 Detection & Monitoring
Log Indicators:
- Web server logs showing requests with unusually long paths or URLs
- PHP error logs containing memory corruption or segmentation fault errors
Network Indicators:
- HTTP requests with path lengths approaching system MAXPATHLEN (typically 4096 bytes)
SIEM Query:
source="web_server_logs" AND (uri_length>4000 OR referer_length>4000)