CVE-2025-4826 Overview
CVE-2025-4826 is a buffer overflow vulnerability affecting TOTOLINK A702R, A3002R, and A3002RU routers running firmware version 3.0.0-B20230809.1615. The flaw resides in the HTTP POST request handler at /boafrm/formWirelessTbl, where the submit-url parameter is processed without proper bounds checking. Attackers can manipulate this argument over the network to overflow a fixed-size buffer. The exploit details have been disclosed publicly, increasing the likelihood of opportunistic attacks against exposed devices. The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-120 (Buffer Copy without Checking Size of Input).
Critical Impact
Remote attackers with low privileges can trigger a buffer overflow in the router web interface, potentially leading to arbitrary code execution or device compromise.
Affected Products
- TOTOLINK A702R firmware 3.0.0-B20230809.1615
- TOTOLINK A3002R firmware 3.0.0-B20230809.1615
- TOTOLINK A3002RU firmware 3.0.0-B20230809.1615
Discovery Timeline
- 2025-05-17 - CVE-2025-4826 published to NVD
- 2025-05-23 - Last updated in NVD database
Technical Details for CVE-2025-4826
Vulnerability Analysis
The vulnerability exists in the boa web server component shipped with the affected TOTOLINK routers. The handler for /boafrm/formWirelessTbl processes HTTP POST requests containing the submit-url parameter. The router copies attacker-supplied data into a fixed-size stack buffer without validating the input length. When an oversized value is supplied, adjacent memory is overwritten, corrupting the stack frame. This corruption can crash the device, alter execution flow, or enable arbitrary code execution depending on payload construction. The boa server typically runs with elevated privileges on these embedded devices, amplifying the consequences of successful exploitation.
Root Cause
The root cause is the use of an unbounded memory copy operation, such as strcpy or sprintf, on attacker-controlled input within the formWirelessTbl handler. The firmware fails to enforce maximum length constraints on the submit-url POST parameter before placing it into a local buffer. This matches the pattern described by CWE-120, where the application trusts external input to determine the destination buffer's required size.
Attack Vector
An attacker sends a crafted HTTP POST request to /boafrm/formWirelessTbl containing an oversized submit-url field. The request can be issued remotely if the router's management interface is reachable from the attacker's network position. While the CVSS vector indicates low privileges are required, this is typically satisfied by access to the local network or to the management interface. Successful exploitation can corrupt the call stack and allow control over the program counter on MIPS or ARM-based router hardware. Technical write-up details are published in the GitHub Documentation and the VulDB entry.
No verified exploit code is included here. Refer to the linked third-party write-ups for proof-of-concept details.
Detection Methods for CVE-2025-4826
Indicators of Compromise
- HTTP POST requests targeting /boafrm/formWirelessTbl containing abnormally long submit-url parameter values.
- Unexpected reboots, web interface crashes, or httpd/boa process restarts on affected TOTOLINK routers.
- Outbound connections from the router to unfamiliar hosts following suspicious POST traffic.
Detection Strategies
- Inspect network traffic to router management interfaces for POST bodies exceeding expected submit-url lengths (typically a handful of bytes).
- Deploy IDS/IPS signatures that flag long URL-style values delivered to boafrm endpoints on TOTOLINK devices.
- Correlate router log anomalies with web request payload sizes captured at perimeter sensors.
Monitoring Recommendations
- Forward router syslog and web server logs to a centralized SIEM and alert on repeated boafrm POST failures.
- Monitor for new device administration sessions originating from untrusted networks.
- Audit WAN-side exposure of TOTOLINK management interfaces using external attack-surface scans.
How to Mitigate CVE-2025-4826
Immediate Actions Required
- Disable remote (WAN) administration on affected TOTOLINK A702R, A3002R, and A3002RU devices.
- Restrict LAN-side access to the web management interface to trusted administrative hosts only.
- Inventory deployed firmware and identify any device running 3.0.0-B20230809.1615.
Patch Information
No vendor patch has been published in the references available for CVE-2025-4826 at the time of NVD publication. Consult the TOTOLINK Official Website for firmware updates and replace the device if updated firmware is not made available for the affected models.
Workarounds
- Place affected routers behind a separate firewall that blocks inbound HTTP/HTTPS access to the management interface.
- Segment the router management VLAN away from user and guest networks.
- Replace end-of-support TOTOLINK models with actively maintained hardware if no firmware fix becomes available.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
