CVE-2025-7420
📋 TL;DR
A critical stack-based buffer overflow vulnerability in Tenda O3V2 routers allows remote attackers to execute arbitrary code by manipulating the extChannel parameter. This affects the router's web interface component httpd and can be exploited without authentication. Anyone using vulnerable Tenda O3V2 routers with internet-facing web interfaces is at risk.
💻 Affected Systems
- Tenda O3V2 router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete router compromise, network traffic interception, lateral movement to internal devices, and persistent backdoor installation.
Likely Case
Router compromise allowing attacker to change network settings, intercept traffic, or use the router as a pivot point for further attacks.
If Mitigated
Limited impact if router is behind firewall with no external web interface access, though internal threats remain possible.
🎯 Exploit Status
Proof-of-concept exploit code is publicly available on GitHub. The vulnerability requires no authentication and has straightforward exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None found in provided references
Restart Required: Yes
Instructions:
1. Check Tenda's official website for firmware updates. 2. Download latest firmware for O3V2 model. 3. Access router web interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Wait for router to reboot.
🔧 Temporary Workarounds
Disable remote web interface access
allPrevent external access to router's web management interface
Access router settings → Administration → Remote Management → Disable
Change default admin password
allWhile this doesn't fix the vulnerability, it adds a layer of protection against other attacks
Access router settings → System Tools → Password → Set strong password
🧯 If You Can't Patch
- Isolate router on separate VLAN with strict firewall rules limiting access to management interface
- Implement network monitoring for unusual traffic patterns or exploit attempts targeting the router
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface: System Status → Firmware Version. If version is 1.0.0.12(3880), device is vulnerable.Check Version:
curl -s http://router-ip/goform/getStatus | grep version (if web interface accessible)Verify Fix Applied:
After firmware update, verify version has changed from 1.0.0.12(3880) to a newer version.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/setWrlBasicInfo with long extChannel parameters
- Router reboot events or configuration changes not initiated by admin
Network Indicators:
- Unusual outbound connections from router to external IPs
- Traffic patterns suggesting router is being used as pivot point
SIEM Query:
source="router_logs" AND (url="/goform/setWrlBasicInfo" AND parameter="extChannel" AND length>100) OR (event="firmware_change" OR event="config_change")🔗 References
- https://github.com/wudipjq/my_vuln/blob/main/Tenda3/vuln_53/53.md
- https://github.com/wudipjq/my_vuln/blob/main/Tenda3/vuln_53/53.md#poc
- https://vuldb.com/?ctiid.315880
- https://vuldb.com/?id.315880
- https://vuldb.com/?submit.608866
- https://www.tenda.com.cn/
- https://github.com/wudipjq/my_vuln/blob/main/Tenda3/vuln_53/53.md
- https://github.com/wudipjq/my_vuln/blob/main/Tenda3/vuln_53/53.md#poc
