CVE-2021-1200
📋 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. Attackers need valid administrator credentials to exploit these input validation flaws in the web management interface. Organizations using Cisco RV110W, RV130, RV130W, or RV215W routers are affected.
💻 Affected Systems
- Cisco RV110W
- Cisco RV130
- Cisco RV130W
- Cisco RV215W
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise with root-level arbitrary code execution, allowing full control of the router and potential lateral movement into connected networks.
Likely Case
Denial of service through device reboots disrupting network connectivity, with potential for authenticated attackers to gain persistent access.
If Mitigated
Limited impact if strong authentication controls prevent unauthorized access to admin credentials and web interface is not exposed.
🎯 Exploit Status
Exploitation requires valid admin credentials but involves simple HTTP request crafting once authenticated.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: None available
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv-overflow-WUnUgv4U
Restart Required: No
Instructions:
No official patch available. Cisco has not released software updates. Consider workarounds or replacement.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the web-based management interface to prevent HTTP-based exploitation
Use CLI: no ip http server
no ip http secure-server
Restrict Management Access
allLimit management interface access to specific trusted IP addresses only
access-list 1 permit [trusted_ip]
ip http access-class 1
🧯 If You Can't Patch
- Replace affected routers with supported models that receive security updates
- Implement network segmentation to isolate vulnerable routers from critical systems
🔍 How to Verify
Check if Vulnerable:
Check router model and firmware version via web interface or CLI 'show version' commandCheck Version:
show versionVerify Fix Applied:
Verify web interface is disabled or access is restricted to specific IPs only📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts followed by successful login
- Unusual HTTP POST requests to management interface
- Device reboot logs without scheduled maintenance
Network Indicators:
- HTTP traffic to router management interface from unexpected sources
- Multiple device reboots in short timeframes
SIEM Query:
source="router_logs" (event_type="authentication" AND result="success") OR (event_type="http_request" AND uri="/admin/*")