CVE-2025-8136 in A702R
Summary
by MITRE • 07/25/2025
A vulnerability, which was classified as critical, was found in TOTOLINK A702R 4.0.0-B20230721.1521. Affected is an unknown function of the file /boafrm/formFilter of the component HTTP POST Request Handler. The manipulation of the argument ip6addr leads to buffer overflow. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used.
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Analysis
by VulDB Data Team • 07/28/2025
The vulnerability identified as CVE-2025-8136 represents a critical buffer overflow flaw within the TOTOLINK A702R router firmware version 4.0.0-B20230721.1521. This security weakness resides in the HTTP POST Request Handler component, specifically within the /boafrm/formFilter file which processes incoming web requests. The vulnerability manifests when the ip6addr argument is manipulated during HTTP POST operations, creating conditions that allow attackers to execute arbitrary code through remote exploitation. The affected device operates with a web-based management interface that accepts user input through form submissions, making this attack vector particularly dangerous as it requires no physical access to the device.
The technical implementation of this buffer overflow vulnerability stems from inadequate input validation within the HTTP POST request handler functionality. When the ip6addr parameter is processed, the application fails to properly bounds-check the input data before copying it into a fixed-size buffer structure. This classic programming error allows an attacker to overflow the allocated memory space, potentially overwriting adjacent memory locations including return addresses and control data. The vulnerability aligns with CWE-121, which specifically addresses stack-based buffer overflow conditions, and may also relate to CWE-787, concerning out-of-bounds write operations. The attack can be executed remotely through the web management interface, eliminating the need for local network access or physical device interaction.
The operational impact of this vulnerability extends beyond simple remote code execution, potentially enabling full system compromise and persistent access to affected networks. An attacker who successfully exploits this vulnerability could gain administrative privileges on the router, allowing them to modify network configurations, establish backdoors, monitor network traffic, or redirect DNS requests. The implications are particularly severe for home and small office networks where these devices often serve as the primary gateway to the internet, creating potential entry points for broader network infiltration. This vulnerability directly maps to ATT&CK technique T1059.007, which involves the use of command and scripting interpreters, and could facilitate further lateral movement within compromised networks through techniques such as T1021.001 for remote services and T1566 for credential access.
Mitigation strategies for CVE-2025-8136 should prioritize immediate firmware updates from TOTOLINK, as this represents the most effective solution to address the underlying buffer overflow condition. Network administrators should implement network segmentation to isolate affected devices from critical network segments and consider disabling remote management interfaces where possible. Additionally, implementing intrusion detection systems with signatures for known exploit patterns and monitoring for unusual HTTP POST requests can help detect exploitation attempts. The use of network access control lists and firewall rules to restrict access to the router's web management interface to trusted IP addresses provides an additional defensive layer. Organizations should also conduct comprehensive vulnerability assessments to identify other potentially affected devices and implement robust patch management processes to ensure timely remediation of similar vulnerabilities across their network infrastructure.