Grandstream GXP1600: root-level flaw opens a silent intercept path

Security researchers disclosed a CVE-2026-2329 flaw that permits remote code execution on the GXP1600 family of desktop VoIP phones used widely in small-to-medium business environments.

The problem stems from a stack-based buffer overflow that an unauthenticated actor can weaponize to obtain root privileges on affected units.

With elevated control, an adversary can extract stored secrets — notably local and SIP account credentials — and redirect voice traffic through attacker-controlled infrastructure.

That pathway produces a near-transparent interception capability: calls continue to ring and connect while media streams are siphoned to a malicious proxy.

Researchers cautioned the exploit is not trivial; it favors operators of moderate skill who can chain code execution to configuration changes.

Grandstream released firmware version 1.0.7.81 slightly more than a week after the issue was disclosed, and public technical write-ups and vendor advisories are available for defenders.

The combination of inexpensive, persistent endpoints and embedded credentials means many small networks expose a long-lived attack surface unless devices are patched or segmented.

Operational mitigations include rapid firmware rollout, network-level isolation of SIP devices, and rotation of any credentials stored on compromised hardware.

Because VoIP endpoints frequently sit on flat LANs, this flaw amplifies the need for Zero Trust micro-segmentation and device-level inventory control in SMB environments.

The event also revives attention on how quickly vendors can produce fixes and how rapidly customers actually deploy them.

For defenders, the priority is clear: validate firmware versions, audit SIP registrar configurations, and treat legacy desktop VoIP gear as high-risk until proven patched.