CVE-2021-1295
📋 TL;DR
This critical vulnerability allows unauthenticated remote attackers to execute arbitrary code as root on affected Cisco Small Business VPN routers. Attackers can exploit it by sending specially crafted HTTP requests to the web management interface. All organizations using the affected router models with exposed management interfaces are at risk.
💻 Affected Systems
- Cisco Small Business RV160
- Cisco Small Business RV160W
- Cisco Small Business RV260
- Cisco Small Business RV260P
- Cisco Small Business RV260W
📦 What is this software?
Rv160w Wireless Ac Vpn Router Firmware by Cisco
View all CVEs affecting Rv160w Wireless Ac Vpn Router Firmware →
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router with root-level access, allowing attackers to intercept all network traffic, install persistent backdoors, pivot to internal networks, or disable network connectivity entirely.
Likely Case
Remote code execution leading to router compromise, credential theft, network traffic interception, and potential lateral movement into connected networks.
If Mitigated
Limited impact if management interface is not internet-facing and proper network segmentation is in place, though internal attackers could still exploit it.
🎯 Exploit Status
Exploitation is straightforward - sending crafted HTTP requests to the management interface. Public proof-of-concept code exists, making weaponization likely.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: RV160/RV160W: 1.0.01.02 or later; RV260/RV260P/RV260W: 1.0.01.04 or later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv160-260-rce-XZeFkNHf
Restart Required: Yes
Instructions:
1. Log into router web interface. 2. Navigate to Administration > Firmware Upgrade. 3. Download appropriate firmware from Cisco website. 4. Upload and install firmware. 5. Reboot router after installation completes.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the web-based management interface to prevent exploitation
Use CLI: configure terminal
no ip http server
no ip http secure-server
end
write memory
Restrict Management Access
allLimit web management interface access to specific trusted IP addresses only
Use web interface: Firewall > ACL > Add rule to allow only specific IPs to port 80/443
Apply and save configuration
🧯 If You Can't Patch
- Immediately disable the web management interface or restrict it to specific management VLANs only
- Implement network segmentation to isolate routers from untrusted networks and monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface (Administration > Firmware Upgrade) or CLI (show version)Check Version:
show versionVerify Fix Applied:
Verify firmware version is at or above the patched versions: RV160/RV160W >= 1.0.01.02, RV260 series >= 1.0.01.04📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to management interface
- Multiple failed authentication attempts followed by successful access
- Unexpected configuration changes
Network Indicators:
- Unusual outbound connections from router
- HTTP requests with unusual parameters to router management interface
- Traffic patterns indicating command and control activity
SIEM Query:
source="router_logs" AND (url="*cgi-bin*" OR url="*login*" OR method="POST") AND status="200" AND user_agent="*curl*" OR user_agent="*python*"