CVE-2025-6887
📋 TL;DR
A critical stack-based buffer overflow vulnerability in Tenda AC5 routers allows remote attackers to execute arbitrary code by sending specially crafted requests to the /goform/SetSysTimeCfg endpoint. This affects Tenda AC5 routers running firmware version 15.03.06.47. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Tenda AC5
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network traffic interception, lateral movement to other devices, and botnet recruitment.
Likely Case
Remote code execution allowing attacker to modify device configuration, intercept traffic, or use device as pivot point for further attacks.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access and proper network segmentation.
🎯 Exploit Status
Public exploit details available in references. Attack requires sending crafted HTTP POST request to vulnerable endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: No
Instructions:
Check Tenda official website for firmware updates. If update available, download and apply through router web interface.
🔧 Temporary Workarounds
Block vulnerable endpoint
linuxUse firewall rules to block access to /goform/SetSysTimeCfg endpoint
iptables -A INPUT -p tcp --dport 80 -m string --string "/goform/SetSysTimeCfg" --algo bm -j DROP
iptables -A INPUT -p tcp --dport 443 -m string --string "/goform/SetSysTimeCfg" --algo bm -j DROP
Disable remote management
allTurn off remote administration features to prevent WAN access
🧯 If You Can't Patch
- Isolate affected routers in separate VLAN with strict firewall rules
- Implement network monitoring for exploit attempts targeting /goform/SetSysTimeCfg
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in web interface or via SSH: cat /proc/version | grep -i tendaCheck Version:
curl -s http://router-ip/ | grep -i firmware || ssh admin@router-ip 'cat /proc/version'Verify Fix Applied:
Verify firmware version is different from 15.03.06.47 and test endpoint with controlled payload📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /goform/SetSysTimeCfg with abnormal time/timeZone parameters
- Router crash/reboot logs
Network Indicators:
- Unusual HTTP traffic to router management interface from external IPs
- POST requests with long strings in time/timeZone parameters
SIEM Query:
source="router-logs" AND (url="/goform/SetSysTimeCfg" AND (param_length("time")>100 OR param_length("timeZone")>100))🔗 References
- https://lavender-bicycle-a5a.notion.site/Tenda-AC5-fromSetSysTime_time-21d53a41781f8002bdb3fe8344d6fd8c?source=copy_link
- https://lavender-bicycle-a5a.notion.site/Tenda-AC5-fromSetSysTime_timeZone-21d53a41781f8021ae2fd2ac639f1b3f?source=copy_link
- https://vuldb.com/?ctiid.314366
- https://vuldb.com/?id.314366
- https://vuldb.com/?submit.603788
- https://vuldb.com/?submit.603789
- https://www.tenda.com.cn/
