CVE-2025-7421 in O3V2
Summary
by MITRE • 07/11/2025
A vulnerability was found in Tenda O3V2 1.0.0.12(3880). It has been rated as critical. This issue affects the function fromMacFilterModify of the file /goform/operateMacFilter of the component httpd. The manipulation of the argument mac leads to stack-based buffer overflow. The attack may be initiated remotely. The exploit has been disclosed to the public and may be used.
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Analysis
by VulDB Data Team • 07/11/2025
The vulnerability identified as CVE-2025-7421 represents a critical stack-based buffer overflow flaw within the Tenda O3V2 router firmware version 1.0.0.12(3880). This vulnerability exists in the httpd web server component and specifically targets the fromMacFilterModify function located within the /goform/operateMacFilter endpoint. The flaw manifests when processing the mac argument parameter, creating a condition where an attacker can manipulate input data to exceed the allocated buffer space on the stack. The exploitation of this vulnerability occurs through remote network access, making it particularly dangerous as it can be triggered without physical access to the device.
The technical nature of this vulnerability places it under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental memory safety issue where data written to a buffer exceeds the buffer's allocated size, potentially overwriting adjacent memory locations. This type of vulnerability is particularly severe because it can lead to arbitrary code execution, allowing attackers to gain full control over the affected device. The attack vector is remote, meaning that malicious actors can exploit this flaw from anywhere on the network without requiring local access or credentials. The fact that public exploits have been disclosed significantly increases the risk level, as it removes the requirement for advanced technical skills to launch successful attacks against vulnerable devices.
The operational impact of CVE-2025-7421 extends beyond simple device compromise, as affected Tenda O3V2 routers could be used as entry points for broader network attacks. Once compromised, these devices can serve as pivoting points for attackers to conduct reconnaissance, launch further attacks against internal network resources, or establish persistent backdoors. The vulnerability affects the core network filtering functionality of the router, potentially allowing unauthorized devices to bypass MAC address filtering mechanisms that are designed to secure network access. This creates a cascading security risk where a single compromised router can undermine the security posture of an entire network infrastructure.
Mitigation strategies for CVE-2025-7421 should prioritize immediate firmware updates from Tenda, as this represents the most effective defense against the known exploit. Network administrators should also implement network segmentation to limit the potential impact of compromised devices, while monitoring network traffic for unusual patterns that might indicate exploitation attempts. Additional protective measures include disabling unnecessary web management interfaces, implementing strong access controls, and maintaining detailed network monitoring to detect unauthorized access attempts. The vulnerability demonstrates the importance of regular firmware updates and security assessments, particularly for network infrastructure devices that are often overlooked in security management programs. Organizations should also consider implementing intrusion detection systems to identify potential exploitation attempts and establish incident response procedures to address successful compromises.