A critical stack overflow vulnerability (CVE-2025-44899) affecting Tenda RX3 routers (firmware V1.0br_V16.03.13.11) has been disclosed, posing risks of remote code execution (RCE) or denial-of-service (DoS). The flaw resides in the `fromSetWifiGuestBasic` function of the `/goform/WifiGuestSet` web interface, triggered by malformed `shareSpeed` parameter input1. With a CVSS score of 9.8 (CRITICAL), this vulnerability underscores recurring security challenges in Tenda’s HTTP request handling.
Technical Breakdown
The vulnerability occurs when the router processes overly long values in the `shareSpeed` parameter during guest Wi-Fi configuration. Improper bounds checking in the firmware’s HTTP handler leads to a stack overflow, potentially allowing attackers to overwrite return addresses or crash the device2. This follows a pattern of similar flaws in Tenda routers, including CVE-2025-45427 (WifiBasicSet) and CVE-2025-29384 (wanMTU overflow in AC9 models)3.
Affected devices expose the vulnerable endpoint by default on both LAN and WAN interfaces if remote administration is enabled. No authentication is required to trigger the overflow, though exploitation complexity depends on stack layout and mitigation features in the specific firmware version.
Impact and Attack Surface
Successful exploitation could permit:
– Remote code execution with router privileges
– Persistent device crashes requiring physical reset
– Network foothold for lateral movement
Tenda RX3 routers are widely deployed in SOHO environments, particularly in regions where the brand dominates budget networking markets. The vulnerability’s public disclosure increases the likelihood of rapid exploit development, given Tenda’s history of similar flaws4.
Mitigation Strategies
Organizations using affected devices should:
1. Apply firmware updates immediately if available from Tenda
2. Disable remote administration on WAN interfaces
3. Segment RX3 routers from critical network segments
4. Monitor for anomalous HTTP requests to `/goform/WifiGuestSet`
As of 2025-05-07, no patches have been released. Temporary workarounds include:
– Blocking access to the web interface from untrusted networks
– Implementing network-based intrusion prevention rules for suspicious HTTP traffic patterns
Detection and Monitoring
Security teams should watch for these indicators:
– Unusually long HTTP parameters in requests to router IPs
– Repeated crashes of RX3 devices
– Unexpected process memory usage spikes on routers
Network monitoring tools can detect exploitation attempts by flagging HTTP requests containing oversized `shareSpeed` values. Sample Suricata rule logic might include:
alert http any any -> $HOME_NET 80 (msg:"Potential CVE-2025-44899 Exploit Attempt";
flow:to_server; content:"POST"; http_method; content:"/goform/WifiGuestSet";
http_uri; content:"shareSpeed="; http_client_body;
pcre:"/shareSpeed=[^\s]{500,}/"; sid:1000001; rev:1;)Conclusion
CVE-2025-44899 represents another critical vulnerability in Tenda’s router firmware, continuing a trend of insufficient input validation in HTTP handlers. While no public exploits exist currently, the high CVSS score and attack simplicity warrant immediate attention. Organizations should prioritize network segmentation and monitoring while awaiting vendor patches.
References
- “CVE-2025-44899 Detail,” NVD, May 2025. [Online]. Available: https://nvd.nist.gov/vuln/detail/CVE-2025-44899
- “GHSA-95mr-cf2h-w5jf,” GitHub Advisory Database, May 2025. [Online]. Available: https://github.com/advisories/GHSA-95mr-cf2h-w5jf
- “CVE-2025-45427 Detail,” NVD, May 2025. [Online]. Available: https://nvd.nist.gov/vuln/detail/CVE-2025-45427
- “CVE-2025-29384,” CVE Details, May 2025. [Online]. Available: https://www.cvedetails.com/cve/CVE-2025-29384
