CVE-2019-11535
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands on Linksys WiFi extender devices (RE6400 and RE6300) by exploiting unsanitized user input in the web interface. Attackers can access system OS configurations and execute commands beyond intended web UI functionality. Users with affected devices running vulnerable firmware versions are at risk.
💻 Affected Systems
- Linksys RE6400
- Linksys RE6300
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to install persistent malware, pivot to internal networks, intercept network traffic, or brick the device.
Likely Case
Attacker gains full control of the extender, can modify network settings, intercept traffic, or use device as foothold for further attacks.
If Mitigated
If properly patched and isolated, minimal impact with only local network access required for exploitation.
🎯 Exploit Status
Exploitation requires network access to web interface but no authentication. Simple command injection via web parameters.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.2.05.001
Vendor Advisory: http://s3.amazonaws.com/downloads.linksys.com/support/assets/releasenotes/Linksys%20RE6300%20RE6400%20Firmware%20Release%20Notes_v1.2.05.001.txt
Restart Required: Yes
Instructions:
1. Download firmware version 1.2.05.001 from Linksys support site. 2. Log into device web interface. 3. Navigate to Administration > Firmware Upgrade. 4. Upload the firmware file. 5. Wait for upgrade to complete and device to reboot.
🔧 Temporary Workarounds
Disable Web Interface
allDisable the vulnerable web interface to prevent exploitation
Not applicable - use device configuration interface
Network Segmentation
allIsolate WiFi extender on separate VLAN to limit attack surface
Not applicable - network configuration required
🧯 If You Can't Patch
- Disconnect device from network until patched
- Place device behind firewall with strict inbound rules
🔍 How to Verify
Check if Vulnerable:
Check firmware version in web interface under Administration > Firmware Upgrade. If version is 1.2.04.022 or earlier, device is vulnerable.Check Version:
Not applicable - check via web interface or device labelVerify Fix Applied:
After patching, verify firmware version shows 1.2.05.001 or later in web interface.📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in system logs
- Multiple failed login attempts to web interface
- Unexpected configuration changes
Network Indicators:
- Unusual outbound connections from extender
- Traffic to suspicious IP addresses
- Port scanning originating from extender
SIEM Query:
source="linksys-extender" AND (event="command_injection" OR event="unauthorized_access")