CVE-2021-1202
📋 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 improper input validation 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 for connected users and services.
If Mitigated
Limited impact if strong credential management prevents unauthorized administrative access.
🎯 Exploit Status
Exploitation requires valid admin credentials but is technically simple once credentials are obtained.
🛠️ 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 for these end-of-life products.
🔧 Temporary Workarounds
Disable web management interface
allDisable the vulnerable web-based management interface entirely
Use CLI: no ip http server
no ip http secure-server
Restrict management access
allLimit web management interface access to specific trusted IP addresses only
ip http access-class [ACL-NAME]
ip http secure-server access-class [ACL-NAME]
🧯 If You Can't Patch
- Replace affected routers with supported models that receive security updates
- Implement network segmentation to isolate vulnerable routers from critical assets
🔍 How to Verify
Check if Vulnerable:
Check router model via CLI: show version | include ModelCheck Version:
show versionVerify Fix Applied:
Verify web interface is disabled: show running-config | include http📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts followed by successful login
- Unusual HTTP requests to management interface
- Device reboot logs without scheduled maintenance
Network Indicators:
- Unusual outbound connections from router
- Traffic patterns suggesting router compromise
SIEM Query:
source="router_logs" (event_type="authentication" AND result="success") | stats count by src_ip, user | where count > threshold