CVE-2021-1291
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to execute arbitrary code as root on affected Cisco Small Business VPN routers. It affects RV160, RV160W, RV260, RV260P, and RV260W models due to improper validation of HTTP requests in the web management interface. Attackers can exploit it by sending crafted HTTP requests to the device's web interface.
💻 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
Full device compromise with root-level arbitrary code execution, enabling attackers to steal data, pivot to internal networks, or disrupt operations.
Likely Case
Remote code execution leading to malware deployment, credential theft, or device takeover for botnet activities.
If Mitigated
Limited impact if devices are patched, isolated, or have web management disabled, reducing attack surface.
🎯 Exploit Status
Exploitation is straightforward due to unauthenticated access and public proof-of-concept code available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.01.02 for RV160/RV160W, 1.0.01.05 for RV260/RV260P/RV260W
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's web interface. 2. Navigate to Administration > Firmware Upgrade. 3. Upload the patched firmware file. 4. Apply the update and allow the router to restart automatically.
🔧 Temporary Workarounds
Disable web management interface
allTurn off the web-based management interface to block HTTP-based exploitation.
Access router CLI via SSH or console, then use: no ip http server and no ip http secure-server
Restrict access via firewall
allLimit access to the web interface to trusted IP addresses only.
Configure firewall rules on the router to allow only specific source IPs to port 80/443
🧯 If You Can't Patch
- Isolate affected routers in a separate network segment to limit lateral movement.
- Monitor network traffic for unusual HTTP requests to the router's management interface.
🔍 How to Verify
Check if Vulnerable:
Check the firmware version in the web interface under Status > Router > Firmware Version.Check Version:
In router CLI: show versionVerify Fix Applied:
Confirm the firmware version matches or exceeds the patched versions listed in the vendor advisory.📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to management URLs
- Failed login attempts followed by successful code execution patterns
Network Indicators:
- Suspicious outbound connections from the router to unknown IPs
- Anomalous traffic spikes on port 80/443
SIEM Query:
source="router_logs" AND (url="*cgi-bin*" OR method="POST") AND status="200"