CVE-2021-1183
📋 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 improper input validation 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 persistent backdoor installation, network traffic interception, and lateral movement to connected systems.
Likely Case
Denial of service through device reboots disrupting network connectivity, potentially combined with limited code execution for reconnaissance.
If Mitigated
No impact if proper credential management prevents unauthorized administrative access and network segmentation limits exposure.
🎯 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 replacement.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the vulnerable web-based management interface and use alternative management methods
Restrict Management Access
allLimit web management interface access to specific trusted IP addresses only
🧯 If You Can't Patch
- Replace affected routers with supported models that receive security updates
- Implement strict network segmentation to isolate vulnerable routers from critical systems
🔍 How to Verify
Check if Vulnerable:
Check router model and firmware version against affected products list. All versions of listed models are vulnerable.Check Version:
Login to router web interface and check System Information or Administration > Firmware Upgrade pageVerify Fix Applied:
No fix available to verify. Verify workarounds by confirming web interface is disabled or access restricted.📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts followed by successful login
- Unusual HTTP POST requests to management interface endpoints
- Device reboot logs without administrative action
Network Indicators:
- HTTP traffic to router management interface from unexpected sources
- Unusual outbound connections from router after management interface access
SIEM Query:
source_ip=router_management_interface AND (http_method=POST AND uri_contains="/admin/") AND status_code=200