CVE-2026-1678
📋 TL;DR
This vulnerability in Zephyr RTOS's DNS resolver allows an out-of-bounds write when processing malicious DNS responses. Attackers can exploit this to potentially execute arbitrary code or crash affected systems. It affects devices running Zephyr RTOS with DNS resolver functionality enabled.
💻 Affected Systems
- Zephyr RTOS
⚠️ 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, data exfiltration, or device takeover
Likely Case
System crash/denial of service, potentially leading to device reboot and service disruption
If Mitigated
Limited impact if DNS resolver is disabled or network controls prevent malicious DNS responses
🎯 Exploit Status
Requires ability to send malicious DNS responses to target device, but no authentication needed
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check latest Zephyr releases for fix
Vendor Advisory: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-536f-h63g-hj42
Restart Required: Yes
Instructions:
1. Update Zephyr RTOS to latest version with fix. 2. Rebuild and redeploy firmware. 3. Restart affected devices.
🔧 Temporary Workarounds
Disable DNS Resolver
allDisable CONFIG_DNS_RESOLVER in build configuration
CONFIG_DNS_RESOLVER=n
Network Segmentation
allRestrict DNS traffic to trusted sources only
🧯 If You Can't Patch
- Disable DNS resolver functionality completely
- Implement strict network controls to filter DNS traffic from untrusted sources
🔍 How to Verify
Check if Vulnerable:
Check if CONFIG_DNS_RESOLVER=y in build configuration and running vulnerable Zephyr versionCheck Version:
Check Zephyr version in build configuration or device firmwareVerify Fix Applied:
Verify Zephyr version includes the fix and CONFIG_DNS_RESOLVER is properly configured📡 Detection & Monitoring
Log Indicators:
- DNS resolver crashes
- Memory corruption errors
- Unexpected device reboots
Network Indicators:
- Unusual DNS response patterns
- DNS traffic from unexpected sources
SIEM Query:
Search for DNS resolver process crashes or memory violation errors in device logs