CVE-2025-6337 Overview
CVE-2025-6337 is a buffer overflow vulnerability affecting TOTOLINK A3002R and A3002RU routers running firmware versions 3.0.0-B20230809.1615 and 4.0.0-B20230531.1404. The flaw resides in the HTTP POST request handler for /boafrm/formTmultiAP, where the submit-url argument is not properly bounded before being copied into a fixed-size buffer. Attackers can trigger memory corruption remotely over the network. The exploit has been publicly disclosed, increasing the risk of opportunistic attacks against exposed devices. The issue is tracked under [CWE-119] and [CWE-120], covering improper restriction of operations within memory buffer bounds.
Critical Impact
Remote attackers with low privileges can corrupt router memory via the submit-url parameter, potentially achieving code execution or denial of service on affected TOTOLINK devices.
Affected Products
- TOTOLINK A3002R firmware 3.0.0-B20230809.1615
- TOTOLINK A3002R firmware 4.0.0-B20230531.1404
- TOTOLINK A3002RU firmware 3.0.0-B20230809.1615 and 4.0.0-B20230531.1404
Discovery Timeline
- 2025-06-20 - CVE-2025-6337 published to NVD
- 2025-08-01 - Last updated in NVD database
Technical Details for CVE-2025-6337
Vulnerability Analysis
The vulnerability lives in the embedded boa web server used by TOTOLINK A3002R and A3002RU routers. The handler routine for /boafrm/formTmultiAP reads the submit-url POST parameter and copies it into a stack-allocated buffer without enforcing a length check. Sending an oversized value overflows the buffer and overwrites adjacent stack data, including the saved return address.
Because the vulnerable endpoint is part of the device's web administration interface, exploitation requires only network reachability to the router's HTTP service. Successful exploitation can corrupt the control flow of the boa process running on the device, which typically executes with elevated privileges on the embedded MIPS or ARM Linux platform.
The EPSS score sits at 1.484% with a percentile of 81.39, indicating elevated likelihood of exploitation activity compared to the broader CVE population. Public disclosure of exploitation details on VulDB and GitHub further reduces the barrier to weaponization.
Root Cause
The root cause is the absence of bounds checking when handling the submit-url argument inside the formTmultiAP HTTP POST handler. The handler trusts attacker-controlled input length, copying data directly into a fixed-size buffer. This pattern matches classic stack-based buffer overflow conditions described by [CWE-120] (Buffer Copy without Checking Size of Input).
Attack Vector
The attack vector is network-based with low attack complexity. An attacker sends a crafted HTTP POST request to /boafrm/formTmultiAP containing an overlong submit-url value. While the CVSS vector indicates low privileges are required, devices left with default credentials or weak authentication remain especially exposed. No user interaction is required to trigger the overflow once the request reaches the device.
The vulnerability mechanism is described in the public references on VulDB and the GitHub CVE Resource #688-13 and GitHub CVE Resource #688-14. No verified proof-of-concept code is reproduced here.
Detection Methods for CVE-2025-6337
Indicators of Compromise
- HTTP POST requests to /boafrm/formTmultiAP containing unusually long submit-url parameter values, especially exceeding a few hundred bytes.
- Unexpected restarts or crashes of the boa web server process on TOTOLINK A3002R/A3002RU devices.
- Outbound connections from the router to unfamiliar hosts following inbound HTTP traffic to the management interface.
- Configuration changes or new firewall rules on the device that were not initiated by an administrator.
Detection Strategies
- Inspect web traffic destined for router management interfaces and flag POST bodies to /boafrm/formTmultiAP with oversized submit-url fields.
- Deploy IDS/IPS signatures matching the URI path /boafrm/formTmultiAP combined with parameter length thresholds.
- Correlate router syslog events with network-edge HTTP logs to identify request bursts targeting the boa server.
Monitoring Recommendations
- Monitor router administration interfaces for exposure to untrusted networks and alert on any inbound HTTP requests from the WAN.
- Centralize firmware version inventory to track devices still running vulnerable builds 3.0.0-B20230809.1615 and 4.0.0-B20230531.1404.
- Track repeated authentication attempts against the router web UI, which often precede exploitation of authenticated endpoints.
How to Mitigate CVE-2025-6337
Immediate Actions Required
- Remove management interface exposure from WAN and untrusted VLANs; restrict access to a dedicated management network.
- Replace default and weak administrator credentials on all TOTOLINK A3002R and A3002RU devices.
- Audit affected devices for unexpected configuration changes, new accounts, or modified DNS settings.
- Where feasible, replace end-of-life or unpatched units with currently supported hardware.
Patch Information
No vendor patch is listed in the NVD references for CVE-2025-6337 at the time of publication. Administrators should consult the TOTOLINK Security Page for firmware updates and subscribe to vendor notifications. Additional technical context is available via VulDB #313333.
Workarounds
- Disable remote (WAN-side) HTTP administration on the affected routers until a fixed firmware is available.
- Place affected devices behind a firewall that blocks inbound HTTP/HTTPS access to the router from any non-management source.
- Apply ACLs that restrict access to /boafrm/formTmultiAP to known administrator IP addresses.
- Segment IoT and network infrastructure devices from user and server networks to limit lateral movement following compromise.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
