CVE-2021-1175
📋 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 Wireless-N VPN Firewall
- Cisco RV130 VPN Router
- Cisco RV130W Wireless-N Multifunction VPN Router
- Cisco RV215W Wireless-N VPN Router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise with root-level arbitrary code execution, allowing full control of the router and potential lateral movement into connected networks.
Likely Case
Device reboot causing temporary denial of service, disrupting network connectivity for connected users and services.
If Mitigated
Limited impact if strong authentication controls prevent unauthorized access to admin credentials.
🎯 Exploit Status
Exploitation requires valid admin credentials but is straightforward once credentials are obtained. No public exploit code was available at advisory publication.
🛠️ 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 to prevent HTTP-based exploitation
Access router CLI via SSH/Telnet
Enter configuration mode
Disable HTTP/HTTPS management service
Restrict Management Access
allLimit web management interface access to specific trusted IP addresses only
Configure firewall rules to restrict access to management IP/port
Set up VPN for management access only
🧯 If You Can't Patch
- Replace affected routers with supported models that receive security updates
- Implement network segmentation to isolate vulnerable routers from critical assets
🔍 How to Verify
Check if Vulnerable:
Check if you have any of the affected Cisco RV models in your inventory. Verify model number via device label or web interface.Check Version:
Log into web interface and check System Information page, or use CLI command 'show version'Verify Fix Applied:
Since no patch exists, verify workarounds by confirming web management 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
- Device reboot logs without authorized maintenance
Network Indicators:
- Unusual outbound connections from router after management interface access
- Traffic patterns suggesting router compromise
SIEM Query:
source="cisco-router" AND (event_type="authentication" AND result="success") AND (src_ip NOT IN trusted_management_ips)