CVE-2025-63938
📋 TL;DR
CVE-2025-63938 is an integer overflow vulnerability in Tinyproxy's strip_return_port() function that could allow remote attackers to cause a denial of service or potentially execute arbitrary code. This affects all Tinyproxy deployments up to version 1.11.2. The vulnerability is triggered when processing specially crafted HTTP requests.
💻 Affected Systems
- Tinyproxy
📦 What is this software?
Tinyproxy by Tinyproxy Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise of the Tinyproxy server
Likely Case
Denial of service causing Tinyproxy to crash or become unresponsive
If Mitigated
Limited impact if proper network segmentation and least privilege principles are followed
🎯 Exploit Status
Proof of concept available in disclosure; exploitation requires sending crafted HTTP requests
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.11.3 and later
Vendor Advisory: https://github.com/tinyproxy/tinyproxy/commit/3c0fde94981b025271ffa1788ae425257841bf5a
Restart Required: Yes
Instructions:
1. Download Tinyproxy 1.11.3 or later from official repository. 2. Compile and install following standard build procedures. 3. Restart Tinyproxy service.
🔧 Temporary Workarounds
Network Filtering
linuxBlock suspicious HTTP requests at network perimeter
iptables -A INPUT -p tcp --dport 8888 -m string --string "malicious_pattern" --algo bm -j DROP
🧯 If You Can't Patch
- Implement network segmentation to isolate Tinyproxy instances
- Deploy web application firewall (WAF) to filter malicious HTTP requests
🔍 How to Verify
Check if Vulnerable:
Check Tinyproxy version: tinyproxy --versionCheck Version:
tinyproxy --versionVerify Fix Applied:
Verify version is 1.11.3 or later and check service status📡 Detection & Monitoring
Log Indicators:
- Unexpected crashes
- Memory allocation errors
- Abnormal request patterns
Network Indicators:
- Unusual HTTP request sizes
- Requests with malformed ports
SIEM Query:
source="tinyproxy.log" AND ("segmentation fault" OR "malloc" OR "overflow")