CVE-2025-8819
📋 TL;DR
A stack-based buffer overflow vulnerability in Linksys WiFi range extenders allows remote attackers to execute arbitrary code by manipulating the staticIp parameter in the setWan function. This affects Linksys RE6250, RE6300, RE6350, RE6500, RE7000, and RE9000 devices with firmware up to August 1, 2025. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Linksys RE6250
- Linksys RE6300
- Linksys RE6350
- Linksys RE6500
- Linksys RE7000
- Linksys RE9000
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, creation of persistent backdoors, lateral movement to connected networks, and botnet recruitment.
Likely Case
Device takeover for credential theft, DNS hijacking, man-in-the-middle attacks against connected clients, or denial of service.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Proof-of-concept exploit code is publicly available on GitHub. The vulnerability requires no authentication and has simple exploitation steps.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: Yes
Instructions:
1. Check Linksys support website for firmware updates. 2. If update available, download and install via web interface. 3. Reboot device after update. 4. Verify firmware version is newer than 20250801.
🔧 Temporary Workarounds
Network Segmentation and Access Control
allIsolate range extenders from untrusted networks and restrict management interface access.
Firewall Rules
linuxBlock external access to device management ports (80, 443, 8080).
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
iptables -A INPUT -p tcp --dport 8080 -j DROP
🧯 If You Can't Patch
- Replace affected devices with patched models or alternative vendors.
- Disable WAN configuration features if not required for device operation.
🔍 How to Verify
Check if Vulnerable:
Check device firmware version via web interface at http://[device-ip]/ or using nmap: nmap -sV -p 80,443 [device-ip]Check Version:
curl -s http://[device-ip]/ | grep -i firmware || snmpwalk -v2c -c public [device-ip] 1.3.6.1.2.1.1.1Verify Fix Applied:
Verify firmware version is newer than 20250801 in device web interface or via SNMP if enabled.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/setWan with long staticIp parameters
- Multiple failed login attempts followed by setWan requests
- Device reboots or configuration changes not initiated by administrators
Network Indicators:
- Unusual outbound connections from range extender devices
- Traffic spikes on management ports
- DNS queries to suspicious domains from device IP
SIEM Query:
source="firewall.log" AND (dst_port=80 OR dst_port=443) AND url="/goform/setWan" AND (staticIp.length>100 OR contains(url,"%00"))🔗 References
- https://github.com/wudipjq/my_vuln/blob/main/Linksys1/vuln_53/53.md
- https://github.com/wudipjq/my_vuln/blob/main/Linksys1/vuln_53/53.md#poc
- https://vuldb.com/?ctiid.319353
- https://vuldb.com/?id.319353
- https://vuldb.com/?submit.626683
- https://www.linksys.com/
- https://github.com/wudipjq/my_vuln/blob/main/Linksys1/vuln_53/53.md
- https://github.com/wudipjq/my_vuln/blob/main/Linksys1/vuln_53/53.md#poc
