CVE-2025-70648 Overview
A stack overflow vulnerability has been identified in the Tenda AX1803 router firmware version 1.0.0.1. The vulnerability exists within the sub_727F4 function, specifically in the handling of the security_5g parameter. This memory corruption flaw allows remote attackers to trigger a Denial of Service (DoS) condition by sending specially crafted network requests to the affected device.
Critical Impact
Network-accessible stack overflow in Tenda AX1803 router allows unauthenticated attackers to crash the device, disrupting network connectivity for all connected users.
Affected Products
- Tenda AX1803 v1.0.0.1
Discovery Timeline
- 2026-01-21 - CVE-2025-70648 published to NVD
- 2026-01-22 - Last updated in NVD database
Technical Details for CVE-2025-70648
Vulnerability Analysis
This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), a memory corruption issue where data written to a buffer on the stack exceeds the allocated size, overwriting adjacent memory regions. The flaw resides in the sub_727F4 function of the Tenda AX1803 firmware, which processes the security_5g parameter without proper bounds checking.
When an attacker supplies an oversized or malformed value for the security_5g parameter, the function writes beyond the allocated stack buffer boundaries. This causes corruption of the stack frame, including the return address and saved registers, ultimately leading to a crash of the affected service or the entire device.
The vulnerability is exploitable remotely over the network without requiring authentication or user interaction, making it particularly dangerous for internet-exposed devices.
Root Cause
The root cause is insufficient input validation and bounds checking in the sub_727F4 function when processing the security_5g parameter. The firmware fails to verify that user-supplied input does not exceed the fixed-size stack buffer allocated for this parameter, allowing attackers to overflow the buffer with crafted input data.
Attack Vector
The attack vector is network-based, requiring an attacker to send a crafted HTTP request to the router's web management interface. The malicious request contains an oversized security_5g parameter value designed to overflow the stack buffer in the vulnerable function.
The attack can be executed without authentication and requires no user interaction. An attacker with network access to the router's management interface can repeatedly trigger the vulnerability to maintain a persistent denial of service condition. Technical details regarding the proof of concept are available in the GitHub PoC for Tenda AX-1803.
Detection Methods for CVE-2025-70648
Indicators of Compromise
- Unexpected router reboots or service interruptions without administrator action
- High volume of HTTP requests targeting router management endpoints with unusually large parameter values
- Memory corruption or crash logs in router system logs referencing the sub_727F4 function
- Network connectivity outages coinciding with suspicious traffic patterns to the router
Detection Strategies
- Deploy network intrusion detection rules to identify HTTP requests with abnormally large security_5g parameter values
- Monitor router availability and implement alerting for unexpected device restarts
- Implement traffic analysis to detect repeated connection attempts to router management interfaces from untrusted sources
- Review access logs for requests containing oversized POST or GET parameters targeting configuration endpoints
Monitoring Recommendations
- Enable logging on network firewalls to capture traffic destined for router management ports
- Implement network segmentation to isolate router management interfaces from untrusted networks
- Deploy SentinelOne Singularity for network visibility to detect anomalous traffic patterns targeting IoT devices
- Establish baseline behavior for router uptime and alert on deviations indicating potential DoS attacks
How to Mitigate CVE-2025-70648
Immediate Actions Required
- Restrict access to the router's web management interface to trusted internal networks only
- Disable remote management features if not required for operations
- Implement firewall rules to block external access to the router's administrative ports
- Monitor for firmware updates from Tenda and apply patches when available
Patch Information
At the time of publication, no official patch has been released by Tenda for this vulnerability. Users should monitor the vendor's official support channels for security updates. The vulnerability was documented in a GitHub PoC for Tenda AX-1803 which provides additional technical context.
Workarounds
- Configure access control lists (ACLs) to permit management interface access only from specific trusted IP addresses
- Place the router behind a properly configured firewall that filters malicious requests
- Consider replacing the affected device with a router from a vendor with active security support if no patch is forthcoming
- Implement network monitoring to quickly detect and respond to DoS conditions
# Example firewall rule to restrict management access (iptables)
# Block external access to router management port (adjust port as needed)
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
