Critical Grandstream Phone System Vulnerability Exposes Calls to Eavesdropping and Interception Attacks
Critical Vulnerability Discovered in Grandstream’s GXP1600 Series VoIP Phones
A critical vulnerability has been discovered in Grandstream’s GXP1600 series VoIP phones, which could allow unauthorized parties to intercept calls. The flaw, identified as CVE-2026-2329, is a stack-based buffer overflow that can be exploited remotely by an attacker to execute code with root privileges on the targeted device.
Vulnerability Details
The GXP1600 series is a line of basic VoIP desktop phones commonly used by small-to-medium businesses. An attacker could exploit the vulnerability to extract sensitive information from vulnerable phones, including local and SIP account credentials. This would enable call interception and eavesdropping, potentially compromising confidential business communications.
However, McKee noted that exploiting the vulnerability requires a certain level of skill and knowledge. “This isn’t a simple exploit that can be carried out with ease,” he said. “But the underlying vulnerability does lower the barrier for potential attackers, and that’s a concern for anyone using these devices in exposed or lightly-segmented environments.”
Previous Exploits and Mitigation
Threat actors have previously targeted Grandstream product vulnerabilities, including using them to recruit devices into botnets. The vulnerability was disclosed to Grandstream in January, and a patched firmware version (1.0.7.81) was released shortly thereafter. Rapid7 has published technical details on the vulnerability, and Grandstream has issued its own advisory.
Grandstream users are advised to update their firmware to the latest version to prevent potential exploitation of the vulnerability. The company has also provided guidance on how to mitigate the risk of attack. As with any critical vulnerability, it is essential for users to take prompt action to protect their devices and sensitive information.
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