CVE-2025-2837: Silabs Gecko OS RCE Vulnerability

CVE-2025-2837 Overview

CVE-2025-2837 is a stack-based buffer overflow [CWE-121] in Silicon Labs Gecko OS that enables remote code execution through malformed HTTP requests. The flaw resides in the HTTP request handling logic, which copies user-supplied data into a fixed-size stack buffer without validating its length. Network-adjacent attackers can exploit the issue without authentication or user interaction. Successful exploitation yields code execution in the context of the affected device. The vulnerability was reported through the Zero Day Initiative as ZDI-CAN-23245 and tracked publicly as ZDI-24-871.

Critical Impact
Unauthenticated adjacent-network attackers can execute arbitrary code on Gecko OS devices by sending crafted HTTP requests, compromising confidentiality, integrity, and availability of the device.

Affected Products

Silicon Labs Gecko OS 1.0.46
Embedded devices and IoT modules running affected Gecko OS firmware
Wi-Fi modules exposing the Gecko OS HTTP service interface

Discovery Timeline

2025-03-26 - CVE-2025-2837 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-2837

Vulnerability Analysis

The vulnerability resides in the HTTP request processing path of Silicon Labs Gecko OS. The HTTP handler reads attacker-controlled fields from incoming requests and copies them into a buffer allocated on the stack. Because the handler does not validate or bound the length of the user-supplied data before the copy, oversized input overflows the destination buffer and overwrites adjacent stack memory, including saved return addresses and control structures. An attacker on the same Wi-Fi network as the device can deliver a single malformed HTTP request to trigger the overflow. Successful exploitation results in arbitrary code execution at the privilege level of the firmware process, which on embedded devices typically equals full device control.

Root Cause

The root cause is missing length validation of user-supplied data prior to a stack buffer copy operation in the HTTP request parser. This pattern matches CWE-121 (Stack-based Buffer Overflow). The firmware assumes well-formed input sizes rather than enforcing explicit bounds checks against the destination buffer size.

Attack Vector

The attack vector is adjacent-network. An attacker must be able to reach the device's HTTP service, typically by joining the same Wi-Fi network or LAN segment. No credentials and no user interaction are required. The attacker sends a crafted HTTP request containing an oversized field, triggering the overflow during request parsing. Refer to the Zero Day Initiative Advisory ZDI-24-871 and the Silicon Labs Community Post for additional technical detail.

Detection Methods for CVE-2025-2837

Indicators of Compromise

HTTP requests to Gecko OS devices containing abnormally long header values, URI components, or body parameters
Unexpected device resets, watchdog reboots, or crash logs correlated with inbound HTTP traffic
Outbound connections from embedded devices to unfamiliar hosts following HTTP traffic spikes
New or unexpected listening services on Gecko OS devices after suspected exploitation

Detection Strategies

Inspect HTTP traffic destined for Gecko OS devices for fields exceeding typical embedded-device limits
Alert on repeated malformed HTTP requests originating from a single host on segments containing IoT devices
Correlate device crash or reboot telemetry with preceding HTTP request patterns
Use signature-based intrusion detection on the Wi-Fi management segment to flag oversized HTTP headers and URIs

Monitoring Recommendations

Forward Gecko OS device logs and Wi-Fi infrastructure logs to a centralized SIEM for correlation
Monitor wireless segments hosting embedded devices for anomalous lateral HTTP activity
Track firmware version inventory to identify devices running Gecko OS 1.0.46 or other affected builds
Establish baselines of normal HTTP request sizes per device class to surface outliers

How to Mitigate CVE-2025-2837

Immediate Actions Required

Identify all devices running Silicon Labs Gecko OS and confirm firmware versions
Restrict network access to the Gecko OS HTTP interface to trusted management hosts only
Place affected devices on isolated VLANs or dedicated SSIDs separated from user and server networks
Disable the HTTP service on Gecko OS devices where it is not operationally required

Patch Information

Silicon Labs has published guidance through its community portal. Review the Silicon Labs Community Post for vendor-supplied remediation details and apply any firmware update referenced for affected products. Validate firmware integrity after upgrade and confirm the device no longer reports the vulnerable version.

Workarounds

Block inbound HTTP traffic to Gecko OS devices at the network boundary when the web interface is not actively used
Apply MAC and IP allow-lists on switches and access points to limit who can reach the device HTTP service
Enforce wireless client isolation on access points serving IoT devices to prevent peer-to-peer exploitation
Decommission unsupported devices that cannot receive a vendor firmware update

bash

# Example: restrict HTTP access to Gecko OS devices via iptables on an upstream gateway
iptables -A FORWARD -p tcp -d <gecko_device_ip> --dport 80 -s <management_host> -j ACCEPT
iptables -A FORWARD -p tcp -d <gecko_device_ip> --dport 80 -j DROP