CVE-2021-1289
📋 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. Organizations using Cisco RV160, RV160W, RV260, RV260P, or RV260W routers are affected.
💻 Affected Systems
- Cisco RV160 VPN Router
- Cisco RV160W VPN Router
- Cisco RV260 VPN Router
- Cisco RV260P VPN Router
- Cisco RV260W VPN Router
📦 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 render the device inoperable.
Likely Case
Remote code execution leading to network surveillance, credential theft, man-in-the-middle attacks, and potential lateral movement into connected networks.
If Mitigated
Limited impact if routers are behind firewalls with restricted web interface access, though risk remains if any exposure exists.
🎯 Exploit Status
Exploitation requires sending crafted HTTP requests to the web interface, which is straightforward for attackers with network access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.01.02 and later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv160-260-rce-XZeFkNHf
Restart Required: Yes
Instructions:
1. Log into the router web interface. 2. Navigate to Administration > Firmware Upgrade. 3. Download firmware version 1.0.01.02 or later from Cisco's website. 4. Upload and install the firmware. 5. The router will reboot automatically.
🔧 Temporary Workarounds
Disable Web Management Interface
allCompletely disable 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 Web Interface Access
allLimit access to the web management interface to trusted IP addresses only.
Use CLI: configure terminal
ip http access-class TRUSTED_ACL
ip http secure-server access-class TRUSTED_ACL
access-list standard TRUSTED_ACL permit [trusted-ip]
end
write memory
🧯 If You Can't Patch
- Immediately restrict web interface access to specific management IP addresses only
- Place routers behind firewalls with strict inbound rules blocking all access to management interfaces
🔍 How to Verify
Check if Vulnerable:
Check firmware version in web interface under Status > Router > Firmware Version or via CLI: show versionCheck Version:
show version | include VersionVerify Fix Applied:
Confirm firmware version is 1.0.01.02 or later using same methods📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to management interface
- Multiple failed login attempts followed by successful access
- Unexpected configuration changes
- Unusual outbound connections from router
Network Indicators:
- HTTP requests with unusual headers or parameters to router management port
- Traffic patterns indicating command and control communication
- Sudden changes in router behavior or performance
SIEM Query:
source="router_logs" AND (http_request="*\x00*" OR http_request="*%00*" OR http_request="*..*" OR http_request="*cmd*" OR http_request="*exec*")