CVE-2021-22359
📋 TL;DR
This is a denial-of-service vulnerability affecting specific Huawei S5700 and S6700 switch models. An attacker can send specially crafted messages to cause service disruption due to insufficient input validation. Organizations using these specific switch versions are affected.
💻 Affected Systems
- Huawei S5700
- Huawei S6700
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete service disruption of affected network switches, causing network downtime and business interruption.
Likely Case
Service degradation or temporary unavailability of affected switches requiring manual intervention.
If Mitigated
Minimal impact if switches are patched, properly segmented, and have input validation controls.
🎯 Exploit Status
Exploitation requires sending specific messages to the device, but exact exploit details are not publicly documented.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to versions beyond V200R005C00SPC500
Vendor Advisory: https://www.huawei.com/en/psirt/security-advisories/huawei-sa-20210519-02-dos-en
Restart Required: Yes
Instructions:
1. Download the latest firmware from Huawei support portal. 2. Backup current configuration. 3. Upload and install the new firmware. 4. Reboot the switch. 5. Verify the update was successful.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to affected switches to trusted management networks only.
Configure ACLs to limit access to switch management interfaces
Input Validation Controls
allImplement additional input validation at network perimeter devices.
Configure firewall rules to filter suspicious traffic patterns
🧯 If You Can't Patch
- Implement strict network segmentation to isolate affected switches from untrusted networks
- Deploy intrusion detection/prevention systems to monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check the switch firmware version using 'display version' command and verify if it matches the affected version.Check Version:
display versionVerify Fix Applied:
After patching, run 'display version' to confirm the firmware version has been updated beyond V200R005C00SPC500.📡 Detection & Monitoring
Log Indicators:
- Unexpected service restarts
- High CPU/memory usage alerts
- Connection drops on affected switches
Network Indicators:
- Unusual traffic patterns to switch management interfaces
- Specific malformed packets targeting switch services
SIEM Query:
source_ip=* AND dest_ip=[switch_ip] AND (event_type="service_crash" OR event_type="high_resource_usage")