CVE-2021-1212
📋 TL;DR
This vulnerability allows authenticated remote attackers to execute arbitrary code as root or cause denial of service on affected Cisco Small Business routers. Attackers need valid administrator credentials to exploit these input validation flaws in the web management interface. Organizations using Cisco RV110W, RV130, RV130W, or RV215W routers are affected.
💻 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 arbitrary code execution, allowing attacker persistence, data theft, and network pivoting.
Likely Case
Device reboot causing temporary denial of service, or limited code execution if attacker has admin credentials.
If Mitigated
No impact if proper network segmentation, credential protection, and access controls are implemented.
🎯 Exploit Status
Exploitation requires valid administrator credentials. Attack involves sending crafted HTTP requests to web interface.
🛠️ 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 available. Follow workarounds and mitigation steps below.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the web-based management interface if not required for operations
Access router CLI via SSH/Telnet
Navigate to management settings
Disable web management interface
Restrict Management Access
allLimit web interface access to specific trusted IP addresses only
Configure firewall rules to restrict access to router management IP
Allow only specific source IPs to port 80/443
🧯 If You Can't Patch
- Implement strict network segmentation to isolate routers from critical networks
- Change all default credentials and implement strong password policies for admin accounts
🔍 How to Verify
Check if Vulnerable:
Check if device model is RV110W, RV130, RV130W, or RV215W and web management interface is enabledCheck Version:
show version (via CLI) or check web interface System Information pageVerify Fix Applied:
Verify web management interface is disabled or access is restricted to trusted IPs only📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts followed by successful login
- Unusual HTTP POST requests to management interface
- Device reboot logs without scheduled maintenance
Network Indicators:
- Unusual outbound connections from router
- HTTP traffic to router management interface from unexpected sources
SIEM Query:
source="router_logs" AND (event="authentication_success" AND user="admin" AND src_ip NOT IN [trusted_ips]) OR (event="device_reboot" AND reason="unexpected")