CVE-2021-1316
📋 TL;DR
This vulnerability allows authenticated remote attackers with administrator credentials to execute arbitrary commands with root privileges on affected Cisco Small Business routers. The vulnerability exists in the web-based management interface due to improper input validation. Attackers can exploit this by sending crafted HTTP requests to gain full control of the device.
💻 Affected Systems
- Cisco Small Business RV016
- RV042
- RV042G
- RV082
- RV320
- RV325 Routers
📦 What is this software?
Rv016 Multi Wan Vpn Router Firmware by Cisco
View all CVEs affecting Rv016 Multi Wan Vpn Router Firmware →
Rv042 Dual Wan Vpn Router Firmware by Cisco
View all CVEs affecting Rv042 Dual Wan Vpn Router Firmware →
Rv042g Dual Gigabit Wan Vpn Router Firmware by Cisco
View all CVEs affecting Rv042g Dual Gigabit Wan Vpn Router Firmware →
Rv082 Dual Wan Vpn Router Firmware by Cisco
View all CVEs affecting Rv082 Dual Wan 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.
Likely Case
Attackers with stolen or compromised admin credentials gain full control of affected routers to monitor traffic, redirect connections, or use as foothold for further attacks.
If Mitigated
With strong credential management and network segmentation, impact is limited to the router itself without lateral movement to other systems.
🎯 Exploit Status
Exploitation requires valid admin credentials but is straightforward once credentials are obtained. Multiple proof-of-concept exploits are publicly available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: RV016: 4.2.3.14, RV042/RV042G: 4.2.3.14, RV082: 4.2.3.14, RV320/RV325: 1.5.1.11
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv-command-inject-BY4c5zd
Restart Required: Yes
Instructions:
1. Log into router web interface as administrator. 2. Navigate to Administration > Firmware Upgrade. 3. Download appropriate firmware from Cisco website. 4. Upload and install firmware. 5. Router will reboot automatically.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the web-based management interface to prevent exploitation via HTTP requests
Configure via CLI: no ip http server
Configure via CLI: no ip http secure-server
Restrict Management Access
allLimit management interface access to specific trusted IP addresses only
Configure via web interface: Firewall > Access Rules to restrict port 80/443
🧯 If You Can't Patch
- Change all administrator passwords to strong, unique credentials
- Disable remote management and only allow local console access
🔍 How to Verify
Check if Vulnerable:
Check current firmware version via web interface: Status > Router > Firmware VersionCheck Version:
Via CLI: show versionVerify Fix Applied:
Verify firmware version matches or exceeds patched versions listed in vendor advisory📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to management interface
- Multiple failed login attempts followed by successful login
- Commands execution in system logs
Network Indicators:
- Unusual outbound connections from router
- HTTP requests with command injection patterns to management interface
SIEM Query:
source="router_logs" AND (http_method="POST" AND uri="/apply.cgi" AND (param="*;*" OR param="*|*" OR param="*`*"))