CVE-2026-1425
📋 TL;DR
A stack-based buffer overflow vulnerability exists in pymumu SmartDNS versions up to 47.1, specifically in the SVCB/HTTPS record parser. This allows remote attackers to potentially execute arbitrary code or crash the service. All systems running vulnerable SmartDNS versions are affected.
💻 Affected Systems
- pymumu SmartDNS
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, allowing attackers to install malware, steal data, or pivot to other systems.
Likely Case
Service crash causing DNS resolution failure and denial of service for dependent applications.
If Mitigated
Limited impact due to exploit complexity and proper network segmentation, potentially only causing service disruption.
🎯 Exploit Status
Attack requires remote access and manipulation of DNS responses. High complexity suggests limited immediate threat.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version after commit 2d57c4b4e1add9b4537aeb403f794a084727e1c8
Vendor Advisory: https://github.com/pymumu/smartdns/commit/2d57c4b4e1add9b4537aeb403f794a084727e1c8
Restart Required: Yes
Instructions:
1. Update SmartDNS to version after commit 2d57c4b4e1add9b4537aeb403f794a084727e1c8. 2. Restart the SmartDNS service. 3. Verify the patch is applied.
🔧 Temporary Workarounds
Disable SVCB/HTTPS Record Support
allTemporarily disable parsing of SVCB/HTTPS records to prevent exploitation
# Add to smartdns.conf: svcb-record no
# Restart service: systemctl restart smartdns
Network Filtering
linuxBlock external DNS responses containing SVCB/HTTPS records at network perimeter
# Example iptables rule (adjust as needed): iptables -A INPUT -p udp --dport 53 -m string --hex-string "|00 40|" --algo bm -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation to isolate SmartDNS instances from untrusted networks.
- Deploy intrusion detection/prevention systems to monitor for buffer overflow attempts in DNS traffic.
🔍 How to Verify
Check if Vulnerable:
Check SmartDNS version with: smartdns -v. If version is 47.1 or earlier, system is vulnerable.Check Version:
smartdns -vVerify Fix Applied:
Verify version is after commit 2d57c4b4e1add9b4537aeb403f794a084727e1c8. Check git log or version string.📡 Detection & Monitoring
Log Indicators:
- SmartDNS crash logs
- Segmentation fault errors in system logs
- Unusual DNS query patterns for SVCB/HTTPS records
Network Indicators:
- Large or malformed DNS responses targeting port 53
- Multiple failed DNS resolution attempts
SIEM Query:
source="smartdns.log" AND ("segmentation fault" OR "buffer overflow" OR "SVCB")