Author: Ameeba

Overview

The vulnerability CVE-2025-8139 is a critical security flaw discovered in TOTOLINK A702R 4.0.0-B20230721.1521. This vulnerability has been classified as critical due to its potential to compromise systems or leak data. The flaw lies within an unknown part of the file /boafrm/formPortFw of HTTP POST Request Handler. This vulnerability has wide-reaching implications, affecting all users of this software and presenting a significant risk due to its potential for remote initiation.
With the vulnerability details now publicly available, it’s critical that users take immediate steps to mitigate the risk. The severity and potential impact of this vulnerability underline the importance of robust cybersecurity practices and timely application of patches and updates.

Vulnerability Summary

CVE ID: CVE-2025-8139
Severity: Critical (8.8 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

TOTOLINK A702R | 4.0.0-B20230721.1521

How the Exploit Works

The vulnerability is a type of buffer overflow attack, a common type of cybersecurity threat. This particular vulnerability is exploited by manipulating the ‘service_type’ argument in an HTTP POST Request to the /boafrm/formPortFw file, leading to an overflow of the buffer. This overflow can potentially allow an attacker to overwrite data in the memory of the system, execute arbitrary code, or cause a system crash.

Conceptual Example Code

Here is a conceptual example of how an HTTP POST request might be manipulated to exploit the vulnerability. This is not actual exploit code, but a simplified version to help understand the process.

POST /boafrm/formPortFw HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
service_type=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA...

In this example, the ‘service_type’ argument is filled with an excessively long string of ‘A’s, causing the buffer to overflow.

Prevention and Mitigation

The primary mitigation strategy for this vulnerability would be to apply the patch provided by the vendor. If a patch is not immediately available, or if it’s not feasible to apply it immediately, a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can be used as temporary mitigation. These can provide some level of protection by detecting and preventing known malicious patterns. However, they should not be considered a long-term solution, and the vendor’s patch should be applied as soon as possible.

Overview

The Common Vulnerabilities and Exposures (CVE) system has recently detailed a critical vulnerability with the identifier CVE-2025-8138, found in TOTOLINK A702R version 4.0.0-B20230721.1521. This vulnerability, if exploited, can lead to serious security breaches, system compromise, and potential data leakage. It is of critical importance to any individual or organization using the affected TOTOLINK product to understand and mitigate this vulnerability as soon as possible.

Vulnerability Summary

CVE ID: CVE-2025-8138
Severity: Critical (CVSS: 8.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

TOTOLINK A702R | 4.0.0-B20230721.1521

How the Exploit Works

The vulnerability resides in an unknown functionality of the file /boafrm/formOneKeyAccessButton in the HTTP POST Request Handler component of the TOTOLINK A702R firmware. The exploitation of this vulnerability involves the manipulation of the ‘submit-url’ argument, which can cause a buffer overflow. This buffer overflow may then result in undefined behavior, potentially leading to system compromise and data leakage.

Conceptual Example Code

An attacker might exploit this vulnerability by sending a maliciously crafted HTTP POST request similar to the following:

POST /boafrm/formOneKeyAccessButton HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
submit-url=www.example.com%00[insert malicious payload here]

In this example, the ‘submit-url’ argument is appended with a null byte (%00) followed by a malicious payload. This causes an overflow in the buffer that stores the ‘submit-url’ data, which can lead to unintended consequences, potentially compromising the system and leaking data.

Mitigation Guidance

It is highly recommended to apply a vendor-supplied patch as soon as possible. If a patch is not immediately available or feasible, consider using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to temporarily mitigate the vulnerability by monitoring network traffic and blocking or alerting on suspicious activity.

Overview

The cybersecurity world is currently dealing with a critical vulnerability identified as CVE-2025-8137. This flaw was discovered in TOTOLINK A702R 4.0.0-B20230721.1521, which is widely used in the networking domain. The severity of the issue is heightened because the vulnerability affects an unknown functionality of the file /boafrm/formIpQoS, a component of the HTTP POST Request Handler. This vulnerability matters because it can potentially lead to system compromise or data leakage, and the exploit has been publicly disclosed, making it accessible to malicious actors.

Vulnerability Summary

CVE ID: CVE-2025-8137
Severity: Critical (CVSS 8.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

TOTOLINK A702R | 4.0.0-B20230721.1521

How the Exploit Works

The vulnerability exploits an argument called ‘mac‘ in the HTTP POST Request Handler. The flaw originates from incorrect buffer handling in the /boafrm/formIpQoS file. The manipulation of the ‘mac’ argument can lead to a buffer overflow condition. Buffer overflow vulnerabilities can allow an attacker to overwrite data in memory, potentially leading to the execution of arbitrary code, system crashes, or a breach of data integrity.

Conceptual Example Code

Although the exact exploit code has not been provided to maintain ethical boundaries, a conceptual example of how this vulnerability might be exploited could look like the following HTTP POST request:

POST /boafrm/formIpQoS HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "mac": "OVERFLOW_STRING" }

In this example, “OVERFLOW_STRING” would be a specially crafted string that is longer than the buffer can handle, causing it to overflow.

Countermeasures and Mitigation

Users are advised to apply the vendor patch as soon as it becomes available to address this vulnerability. In the meantime, implementing a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as temporary mitigation, helping to detect and prevent exploit attempts. Regularly updating and patching your systems is the best measure to protect against such vulnerabilities.

Overview

CVE-2025-8136 is a critical vulnerability discovered in TOTOLINK A702R 4.0.0-B20230721.1521. This vulnerability is particularly concerning as it affects the HTTP POST Request Handler, one of the most critical components of a web server. More specifically, the issue arises in an undisclosed function of the file /boafrm/formFilter. The vulnerability can be exploited remotely, meaning that an attacker does not need physical access to the device to compromise it. Therefore, it is essential for organizations using TOTOLINK A702R to address this issue promptly to prevent potential system compromise or data leakage.

Vulnerability Summary

CVE ID: CVE-2025-8136
Severity: Critical (8.8 CVSS Severity Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise and potential data leakage

Affected Products

Product | Affected Versions

TOTOLINK A702R | 4.0.0-B20230721.1521

How the Exploit Works

The exploit works by manipulating the ‘ip6addr’ argument within the HTTP POST Request Handler. This manipulation causes a buffer overflow in the system. In computing, a buffer overflow occurs when data written to a buffer exceeds its storage capacity, causing the extra data to overflow into adjacent memory locations. This overflow can overwrite other data, crash the system, or lead to the execution of malicious code, potentially granting an attacker control over the system.

Conceptual Example Code

Below is a conceptual example of how the vulnerability might be exploited using a malicious HTTP POST request.

POST /boafrm/formFilter HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "ip6addr": "2001:0db8:85a3:0000:0000:8a2e:0370:7334" + "A"*10000 }

In this example, the ‘ip6addr’ argument is filled with a legitimate IPv6 address, followed by a large number of ‘A’ characters. The excessive ‘A’ characters cause a buffer overflow, potentially allowing an attacker to compromise the system.

Mitigation Measures

Users of TOTOLINK A702R 4.0.0-B20230721.1521 are advised to apply the vendor patch as soon as it becomes available. In the meantime, temporary mitigation strategies could include the use of a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to monitor network traffic and block any suspicious activity. It’s also advisable to restrict access to the affected device to trusted networks only, until the patch is applied.