CVE-2021-1198
📋 TL;DR
This vulnerability allows authenticated attackers with administrator credentials to execute arbitrary code as root or cause denial of service on affected Cisco Small Business routers. It affects RV110W, RV130, RV130W, and RV215W routers through improper input validation in the web management interface. Attackers can exploit it by sending crafted HTTP requests to vulnerable devices.
💻 Affected Systems
- Cisco RV110W
- Cisco RV130
- Cisco RV130W
- Cisco RV215W
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise with root-level code execution, allowing attackers to install persistent malware, intercept all network traffic, or use the device as a pivot point into the network.
Likely Case
Device reboot causing temporary service disruption, or limited code execution if attackers have admin credentials but lack sophisticated payloads.
If Mitigated
No impact if proper network segmentation, credential management, and access controls prevent attackers from reaching the management interface.
🎯 Exploit Status
Exploitation requires valid administrator credentials but is technically simple once credentials are obtained. No public exploit code is known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: None available
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv-overflow-WUnUgv4U
Restart Required: No
Instructions:
No official patch is available from Cisco. Consider workarounds or device replacement.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the web-based management interface and use alternative management methods like CLI or dedicated management networks.
Access router CLI via SSH/Telnet
Navigate to management settings
Disable HTTP/HTTPS management services
Restrict Management Access
allLimit management interface access to specific trusted IP addresses or VLANs only.
Configure ACLs to restrict access to management IP
Set up management VLAN separate from user traffic
🧯 If You Can't Patch
- Replace affected devices with supported models that receive security updates
- Implement network segmentation to isolate affected routers from critical assets
🔍 How to Verify
Check if Vulnerable:
Check if you have RV110W, RV130, RV130W, or RV215W routers with web management enabled. Review device logs for suspicious HTTP requests to management interface.Check Version:
show version (via CLI) or check web interface System Information pageVerify Fix Applied:
Verify web management interface is disabled or access is restricted. Test from unauthorized networks to confirm access is blocked.📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts followed by successful login
- Unusual HTTP POST requests to management URLs
- Device reboot logs without authorized cause
Network Indicators:
- HTTP traffic to router management interface from unexpected sources
- Unusual outbound connections from router after management access
SIEM Query:
source="router_logs" AND (event_type="authentication" AND result="success" AND user="admin") OR (url_path="/admin/*" AND http_method="POST" AND size>normal)