CVE-2026-35085: Stack buffer overflow in method gdv-serverconfig

Synopsis

A stack-based buffer overflow exists in the gdv-serverconfig method across multiple MBS device variants (Single-A, Double-A Profibus, Double-A x-link, Single-X, Double-X CAN, Double-X DALI, Double-X KNX, and Double-X LON) running firmware versions from V1_0_0_0 up to but not including V6_0_0_7. The vulnerability is reachable over the network and requires only a low-privilege user account to trigger, meaning no admin credentials are needed. Successful exploitation gives the attacker full root-level control of the affected system, enabling arbitrary code execution, data access, and service disruption. A patched-image rebuild at V6_0_0_7 is available on HarborGuard for environments running an affected version.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must reach the gdv-serverconfig service over the network; the CVSS vector specifies AV:N, meaning no local or physical access is needed.

• AuthenticationRequired

  A low-privilege user account is sufficient to trigger the overflow; no administrative or elevated credentials are required (PR:L).

• Victim interactionNot required

  The attack is fully attacker-driven and requires no action from any user on the target system (UI:N).

• Attack complexityDetail

  Attack complexity is low (AC:L), meaning the exploit is reliable and does not depend on race conditions, specific memory layouts, or other variable environmental factors.

Blast Radius

• A successful attacker gains root-level code execution on the affected device, allowing installation of arbitrary software or backdoors.
• The attacker can read all data stored or processed on the system, including configuration secrets, credentials, and operational data.
• The attacker can modify persisted configuration, firmware state, or application data on the device.
• The attacker can crash or disable the affected service or the entire device, causing a loss of availability for any systems or processes that depend on it.