CVE-2025-8414: Zigbee EZSP Buffer Overflow Vulnerability

CVE-2025-8414 Overview

CVE-2025-8414 is a buffer overflow vulnerability in Silicon Labs Zigbee EZSP (EmberZNet Serial Protocol) Host Applications. The flaw stems from improper input validation [CWE-20], which allows attacker-controlled data to overflow a stack buffer. Stack corruption can occur when the overflow is triggered, and under specific conditions this leads to arbitrary code execution on the host application. Exploitation requires possession of a valid Zigbee network key and adjacent-network access to the target. The vulnerability affects Zigbee deployments where host MCUs communicate with Silicon Labs network co-processors using EZSP, a configuration common in smart home hubs, industrial gateways, and IoT bridges.

Critical Impact

Successful exploitation enables arbitrary code execution on the Zigbee host application through stack corruption, compromising downstream IoT and gateway devices.

Affected Products

• Silicon Labs Zigbee EZSP Host Applications
• Devices integrating EmberZNet host-side stacks over EZSP
• IoT gateways and hubs using Silicon Labs Zigbee network co-processors

Discovery Timeline

• 2025-10-17 - CVE-2025-8414 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-8414

Vulnerability Analysis

The vulnerability resides in the Zigbee EZSP Host Application code path that processes data received from the Zigbee network. EZSP is the serial protocol used between a host processor and a Silicon Labs network co-processor handling the Zigbee radio. Host-side parsing routines fail to validate the length of incoming fields before copying them into fixed-size stack buffers. When a crafted frame exceeds the expected size, adjacent stack memory is overwritten, including saved return addresses and frame pointers.

An attacker with the network key can craft and inject malformed Zigbee frames that traverse the network co-processor and reach the vulnerable host parser. The resulting stack corruption can be steered toward arbitrary code execution on the host application, which often runs with elevated privileges on a gateway or hub.

Root Cause

The root cause is improper input validation [CWE-20] in the EZSP host-side message handler. Length and bounds checks on attacker-controllable fields are missing or insufficient before the data is copied into stack-allocated buffers. This combination of unchecked input and bounded local storage produces a classic stack-based buffer overflow.

Attack Vector

Exploitation requires adjacent-network access to the Zigbee network and possession of a valid network key. An authenticated participant in the Zigbee personal area network (PAN) sends crafted application or protocol frames that propagate to the target host through the EZSP interface. No user interaction is required on the target. Because the network key is shared among joined devices, a single compromised endpoint within the PAN provides sufficient access to mount the attack.

No public proof-of-concept code is available. Refer to the Silicon Labs Community Resource for vendor-provided technical details.

Detection Methods for CVE-2025-8414

Indicators of Compromise

• Unexpected restarts, crashes, or watchdog resets on Zigbee gateways and hubs running EZSP host software.
• Anomalous outbound network connections originating from IoT gateway devices that previously communicated only with cloud control planes.
• Malformed or oversized Zigbee frames observed in PAN traffic captures from joined endpoints.

Detection Strategies

• Monitor host-side EZSP logs for parser errors, truncated frames, and assertion failures that may indicate exploitation attempts.
• Baseline normal Zigbee frame sizes per cluster and alert on frames exceeding expected bounds at the host application layer.
• Correlate gateway process crashes with subsequent privilege-sensitive activity such as new persistence, configuration changes, or lateral movement.

Monitoring Recommendations

• Enable verbose EZSP frame logging on host applications during the patch rollout window to capture suspicious payloads.
• Inventory all devices joined to each Zigbee PAN and alert on unexpected joins or rejoins, which can precede network key abuse.
• Forward gateway syslog and process telemetry to a centralized analytics platform for cross-device correlation.

How to Mitigate CVE-2025-8414

Immediate Actions Required

• Identify all gateways, hubs, and embedded devices running Silicon Labs Zigbee EZSP host applications and inventory their firmware versions.
• Apply vendor-provided updates to the EZSP host application as soon as they are available from Silicon Labs.
• Rotate Zigbee network keys on PANs where the integrity of joined devices cannot be verified.

Patch Information

Consult the Silicon Labs Community Resource for the authoritative advisory, fixed versions, and upgrade guidance. Coordinate firmware updates with device manufacturers that ship Silicon Labs EZSP host stacks in their products.

Workarounds

• Restrict Zigbee network membership to known, trusted devices and disable open join windows except during commissioning.
• Segment IoT gateways from sensitive enterprise networks so a compromised host cannot reach high-value assets.
• Increase scrutiny of devices joining the PAN and monitor for repeated rejoins, which can indicate attacker reconnaissance against the EZSP host.