CVE-2025-2962
📋 TL;DR
This CVE describes a denial-of-service vulnerability in the DNS implementation that could cause an infinite loop when processing certain DNS responses. This affects systems running Zephyr RTOS with DNS functionality enabled. The vulnerability allows remote attackers to crash or hang affected systems by sending malicious DNS packets.
💻 Affected Systems
- Zephyr RTOS
📦 What is this software?
Zephyr by Zephyrproject
⚠️ Risk & Real-World Impact
Worst Case
Complete system crash or indefinite hang requiring manual reboot, potentially disrupting critical operations in embedded/IoT devices.
Likely Case
Service disruption affecting DNS-dependent functionality, causing temporary unavailability until system restart.
If Mitigated
Minimal impact if DNS functionality is disabled or systems are behind network filtering.
🎯 Exploit Status
Exploitation requires sending specially crafted DNS responses to trigger the infinite loop condition.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Zephyr security advisory for specific patched versions
Vendor Advisory: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-2qp5-c2vq-g2ww
Restart Required: Yes
Instructions:
1. Review Zephyr security advisory GHSA-2qp5-c2vq-g2ww. 2. Update to patched Zephyr version. 3. Rebuild and redeploy affected firmware. 4. Restart devices.
🔧 Temporary Workarounds
Disable DNS functionality
allDisable DNS client functionality if not required
Modify Zephyr configuration to disable CONFIG_DNS_RESOLVER
Network filtering
allBlock or filter incoming DNS responses at network perimeter
🧯 If You Can't Patch
- Implement network-level DNS response filtering and validation
- Isolate affected systems in segmented network zones with restricted DNS access
🔍 How to Verify
Check if Vulnerable:
Check Zephyr version and configuration for DNS resolver enabledCheck Version:
Check Zephyr build configuration and version metadataVerify Fix Applied:
Verify Zephyr version is updated to patched release and test DNS functionality📡 Detection & Monitoring
Log Indicators:
- System hangs or crashes during DNS resolution
- High CPU usage from DNS tasks
- DNS timeout errors
Network Indicators:
- Unusual DNS response patterns to affected systems
- DNS traffic causing system unresponsiveness
SIEM Query:
Search for: (event_type:crash OR event_type:hang) AND process_name:dns* OR (dns_response AND system_unresponsive)