CVE-2025-9782 Overview
CVE-2025-9782 is a buffer overflow vulnerability in the TOTOLINK A702R router running firmware version 4.0.0-B20211108.1423. The flaw resides in the sub_4466F8 function processing requests to /boafrm/formOneKeyAccessButton. Attackers manipulate the submit-url argument to overflow a fixed-size buffer in the web management interface. The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). Remote attackers can trigger the condition over the network, and a public proof-of-concept exists in the rew1X GitHub repository.
Critical Impact
A remote authenticated attacker can corrupt memory in the router's web server, potentially achieving arbitrary code execution and full device compromise.
Affected Products
- TOTOLINK A702R router (hardware)
- TOTOLINK A702R firmware version 4.0.0-B20211108.1423
- Deployments exposing the web management interface to untrusted networks
Discovery Timeline
- 2025-09-01 - CVE-2025-9782 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-9782
Vulnerability Analysis
The TOTOLINK A702R exposes a web-based administration interface through the boa HTTP server. The handler routine sub_4466F8 processes POST requests sent to the endpoint /boafrm/formOneKeyAccessButton. This function reads the submit-url parameter from the request body and copies it into a stack-resident buffer without validating the input length.
When an attacker submits a submit-url value longer than the destination buffer, adjacent stack memory is overwritten. This includes saved return addresses and local variables. On MIPS-based embedded targets like the A702R, controlled overwrites of the return address allow attackers to redirect execution flow. The web server typically runs with elevated privileges on consumer routers, meaning successful exploitation grants control over network traffic, DNS settings, and device firmware.
Root Cause
The root cause is missing bounds checking in the sub_4466F8 request handler. The function uses an unsafe string copy operation, likely strcpy or sprintf, against user-supplied input. No length validation occurs before the copy. This pattern is common across the TOTOLINK boafrm form handlers and reflects systemic input validation weaknesses in the firmware.
Attack Vector
The attack vector is network-based and requires low-privilege authentication to the router's web interface. An attacker reaches the vulnerable endpoint by submitting a crafted HTTP POST request to /boafrm/formOneKeyAccessButton containing an oversized submit-url parameter. The exploit is published, lowering the barrier for opportunistic attackers scanning for exposed TOTOLINK devices. Refer to the published proof-of-concept analysis for the exact request structure.
Detection Methods for CVE-2025-9782
Indicators of Compromise
- HTTP POST requests to /boafrm/formOneKeyAccessButton containing submit-url parameter values exceeding several hundred bytes
- Unexpected reboots or crashes of the router's boa web server process
- Outbound connections from the router to unfamiliar IP addresses, suggesting post-exploitation callbacks
- Unauthorized configuration changes, including DNS resolver or firmware update URL modifications
Detection Strategies
- Inspect HTTP request logs from network monitoring appliances for oversized POST bodies directed at TOTOLINK boafrm endpoints
- Deploy intrusion detection signatures that match overly long submit-url field values in HTTP traffic
- Correlate device crash events with preceding HTTP traffic to identify exploitation attempts
Monitoring Recommendations
- Forward router syslog data to a centralized SIEM for retention and correlation
- Alert on administrative login activity from non-trusted source IPs
- Monitor DNS queries originating from router IPs for signs of compromise such as resolution of attacker-controlled domains
How to Mitigate CVE-2025-9782
Immediate Actions Required
- Restrict access to the router's web management interface to trusted LAN clients and disable remote (WAN-side) administration
- Change default and weak administrator credentials to reduce the risk of authenticated exploitation
- Place affected TOTOLINK A702R devices behind a network segment that filters inbound HTTP traffic to management endpoints
- Audit the device for unauthorized configuration changes, particularly DNS and firmware settings
Patch Information
No vendor patch is currently referenced in the NVD record for CVE-2025-9782. Administrators should monitor the TOTOLINK official website for firmware updates addressing the formOneKeyAccessButton handler. Until a fixed firmware release is available, consider replacing affected devices with hardware from vendors that provide active security maintenance.
Workarounds
- Disable the web management interface on the WAN side through router settings
- Apply firewall rules upstream that block HTTP and HTTPS traffic destined for the router's administrative IP from untrusted networks
- Segment IoT and consumer router devices onto isolated VLANs to limit lateral movement following a successful compromise
- Decommission and replace end-of-life TOTOLINK A702R units in high-risk deployments
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
