Overview
In the ever-evolving world of cybersecurity, new vulnerabilities are a common occurrence. One such critical vulnerability has been discovered in TOTOLINK A702R version 4.0.0-B20211108.1423. This vulnerability, assigned the identifier CVE-2025-9781, is a severe threat to all users of the affected product as the exploit can be initiated remotely, potentially leading to system compromise or data leakage.
This vulnerability is particularly concerning due to the high CVSS severity score of 8.8, indicating a high impact upon successful exploitation. This blog post aims to detail the vulnerability, its impact, and the necessary steps to mitigate the threat.
Vulnerability Summary
CVE ID: CVE-2025-9781
Severity: Critical (8.8 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage
Affected Products
Escape the Surveillance Era
Most apps won’t tell you the truth.
They’re part of the problem.
Phone numbers. Emails. Profiles. Logs.
It’s all fuel for surveillance.
Ameeba Chat gives you a way out.
- • No phone number
- • No email
- • No personal info
- • Anonymous aliases
- • End-to-end encrypted
Chat without a trace.
Product | Affected Versions
TOTOLINK A702R | 4.0.0-B20211108.1423
How the Exploit Works
The vulnerability lies in the handling of the ‘ip6addr’ argument in the function ‘sub_4162DC’ of the file ‘/boafrm/formFilter’. By manipulating this argument, an attacker can cause a buffer overflow condition. Buffer overflows occur when more data is written to a piece of memory than it can handle, which can cause data to spill over into adjacent memory spaces.
In this case, an attacker could send a specially crafted request containing a long ‘ip6addr’ argument to the target device. This overflow can corrupt memory and potentially allow for the execution of arbitrary code or cause a denial of service.
Conceptual Example Code
Here is a conceptual example of how the vulnerability might be exploited:
POST /boafrm/formFilter HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
ip6addr=0201:0db8:85a3:0000:0000:8a2e:0370:7334...[additional data]In this example, the ‘ip6addr’ argument is filled with more data than it can handle, leading to a buffer overflow.
Please note that this is a simplified and conceptual example. Real-world exploits may involve additional techniques or steps to successfully exploit the vulnerability.
Mitigation
The vendor has issued a patch for the affected product. Users are strongly advised to apply this patch immediately. If unable to patch immediately, users should consider using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) as a temporary mitigation measure, although these are not guaranteed to fully protect against the exploit.
