CVE-2021-1194
📋 TL;DR
Multiple input validation vulnerabilities in Cisco Small Business RV series routers allow authenticated remote attackers to execute arbitrary code as root or cause denial of service. Attackers need valid administrator credentials to exploit these vulnerabilities. Affected devices include RV110W, RV130, RV130W, and RV215W routers.
💻 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 persistent backdoor installation, network traffic interception, and lateral movement to connected systems.
Likely Case
Authenticated attackers gaining full control of affected routers, potentially disrupting network connectivity and accessing sensitive network traffic.
If Mitigated
Limited to denial of service if code execution fails, causing temporary network disruption until device reboots.
🎯 Exploit Status
Exploitation requires valid admin credentials but involves simple HTTP request crafting once authenticated.
🛠️ 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. Cisco has not released software updates. Consider workarounds or device replacement.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the vulnerable web-based management interface to prevent exploitation
Access router CLI via SSH/Telnet
Navigate to web management settings
Disable HTTP/HTTPS management access
Restrict Management Access
allLimit web management interface access to specific trusted IP addresses only
Configure firewall rules to restrict access to management IP
Set up VPN for management access only
🧯 If You Can't Patch
- Replace affected devices with supported models that receive security updates
- Implement network segmentation to isolate vulnerable routers from critical systems
🔍 How to Verify
Check if Vulnerable:
Check device model and firmware version against affected products list. If using RV110W, RV130, RV130W, or RV215W, assume vulnerable.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 to trusted IPs only📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to management interface
- Multiple authentication attempts followed by crafted requests
- Device reboot logs without normal shutdown
Network Indicators:
- HTTP traffic to router management interface from unexpected sources
- Unusual outbound connections from router after exploitation
SIEM Query:
source_ip="router_management_interface" AND (http_method="POST" AND uri_contains="/admin/") AND size_bytes>threshold