CVE-2021-1181
📋 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 Small Business RV110W
- Cisco Small Business RV130
- Cisco Small Business RV130W
- Cisco Small Business RV215W
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise with root-level arbitrary code execution, allowing attackers to intercept traffic, modify configurations, or use the device as a pivot point into the network.
Likely Case
Device reboot causing temporary denial of service, or limited code execution if attackers have admin credentials but lack sophisticated payloads.
If Mitigated
No impact if devices are properly segmented, admin credentials are secured, and web management interface is disabled or restricted.
🎯 Exploit Status
Exploitation requires valid administrator credentials but involves simple HTTP request crafting once credentials are obtained.
🛠️ 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 replacement.
🔧 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 web management settings
Disable HTTP/HTTPS management
Restrict Management Access
allLimit web management interface access to specific trusted IP addresses only
Configure firewall rules on router
Set management interface ACLs
Allow only specific source IPs
🧯 If You Can't Patch
- Replace affected routers with supported models that receive security updates
- Segment affected routers in isolated network zones with strict firewall rules
🔍 How to Verify
Check if Vulnerable:
Check if you have any Cisco RV110W, RV130, RV130W, or RV215W routers in your inventoryCheck Version:
show version (via CLI) or check web interface System Information pageVerify Fix Applied:
Verify web management interface is disabled or restricted, or confirm router replacement📡 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:
- HTTP traffic to router management interface from unexpected sources
- Unusual outbound connections from router after management interface access
SIEM Query:
source="router_logs" (event="authentication success" AND user="admin") OR (event="device reboot" AND NOT reason="scheduled")