CVE-2021-1169
📋 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. It affects users of RV110W, RV130, RV130W, and RV215W routers with web-based management enabled. Attackers need valid administrator credentials to exploit it.
💻 Affected Systems
- Cisco Small Business RV110W Router
- Cisco Small Business RV130 Router
- Cisco Small Business RV130W Router
- Cisco Small Business RV215W Router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise via remote code execution as root, leading to data theft, network manipulation, or persistent backdoor installation.
Likely Case
Denial of service from device reboots, disrupting network connectivity and business operations.
If Mitigated
Limited impact if strong access controls and network segmentation are in place, reducing exposure to authenticated threats.
🎯 Exploit Status
Exploitation requires authenticated access; complexity is low due to improper input validation in the web interface.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: None
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv-overflow-WUnUgv4U
Restart Required: No
Instructions:
No official patch available; follow workarounds and mitigation steps as per vendor advisory.
🔧 Temporary Workarounds
Disable Web-Based Management Interface
allTurn off the web management interface to prevent HTTP-based exploitation.
Access router CLI via SSH or console, then use command: no ip http server
Or use web interface to disable HTTP/HTTPS management under Administration > Management.
Restrict Access to Management Interface
allLimit management access to trusted IP addresses using ACLs.
Configure access control lists (ACLs) on the router to allow only specific IPs to the management interface.
🧯 If You Can't Patch
- Replace affected routers with supported models that receive security updates.
- Implement network segmentation to isolate routers from critical systems and monitor for anomalous traffic.
🔍 How to Verify
Check if Vulnerable:
Check if you are using an affected router model (RV110W, RV130, RV130W, RV215W) and if web management is enabled.Check Version:
Log into router web interface or CLI and check firmware version under Status > Router or using command: show versionVerify Fix Applied:
Verify that web management interface is disabled or access is restricted, and monitor for any unauthorized changes or reboots.📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to management interface, multiple failed login attempts followed by successful admin access, or unexpected device reboots in logs.
Network Indicators:
- Suspicious traffic patterns to router management ports (e.g., TCP/80, TCP/443) from unauthorized sources.
SIEM Query:
Example: source_ip="router_ip" AND (http_method="POST" OR http_method="GET") AND uri CONTAINS "/admin/" AND status_code=200