CVE-2026-89034: TCH QRing Smart Ring Auth Bypass Flaw

CVE-2026-89034 Overview

CVE-2026-89034 affects the TCH QRing smart ring model R20_B006 running firmware RT09R20_1.00.00_250318. The device exposes a Nordic UART Service (NUS) over Bluetooth Low Energy (BLE) without any client authentication, pairing requirement, or command authorization. Any attacker within BLE range can connect directly to the ring, bypass the official mobile application, and bypass cloud authentication. Once connected, attackers can read battery levels, activate live heart rate monitoring, and retrieve stored historical heart rate and blood oxygen records. The flaw is classified as Missing Authentication for Critical Function [CWE-306].

Critical Impact

An adjacent attacker can retrieve stored biometric data, including heart rate and blood oxygen history, from any TCH QRing device in BLE range without user interaction.

Affected Products

• TCH QRing smart ring, hardware model R20_B006
• Firmware version RT09R20_1.00.00_250318
• Devices exposing the Nordic UART Service without client authentication

Discovery Timeline

• 2026-09-16 - CVE-2026-89034 published to the National Vulnerability Database
• 2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-89034

Vulnerability Analysis

The TCH QRing exposes the Nordic UART Service, a common BLE GATT service used to tunnel serial-style commands between a peripheral and a central. On the affected firmware, the service accepts writes to its RX characteristic and streams responses over its TX characteristic without requiring BLE pairing, bonding, or any application-layer authentication. This design collapses the trust boundary that the vendor's mobile application and cloud service were expected to enforce.

Any attacker within BLE range can therefore issue proprietary commands directly to the ring. The device honors requests for battery status, live heart rate activation, and dumps of stored heart rate and SpO2 records. Because the ring stores biometric history locally, the impact is not limited to the moment of the attack; historical health telemetry is exfiltrated in a single session.

Root Cause

The root cause is Missing Authentication for Critical Function [CWE-306]. The firmware neither requires BLE Secure Connections pairing nor enforces an application-layer challenge before executing sensitive commands. Command handlers do not verify caller identity, so the mobile app's cloud-backed authentication is trivially bypassed by talking to the GATT stack directly.

Attack Vector

Exploitation requires only BLE proximity to the target ring. An attacker uses a generic BLE central (for example, a laptop with a BLE adapter or a mobile device running a GATT explorer) to scan for the ring, connect without pairing, enable notifications on the NUS TX characteristic, and write vendor command frames to the RX characteristic. The ring responds with the requested telemetry. No user prompt is displayed on the ring or the paired phone.

Technical details and command traces are documented in the MrVar0x blog on smart ring reverse engineering and the accompanying MrVar0x white paper.

Detection Methods for CVE-2026-89034

Indicators of Compromise

• Unexpected BLE GATT connections to the ring from devices other than the user's paired phone.
• Battery drain or unexpected live heart rate sessions triggered while the official application is closed.
• Presence of the Nordic UART Service UUID (6E400001-B5A3-F393-E0A9-E50E24DCCA9E) advertised by the ring with no bonding requirement.

Detection Strategies

• Perform BLE traffic capture in sensitive areas using sniffers such as Ubertooth, nRF Sniffer, or Sniffle to observe unauthenticated writes to the NUS RX characteristic.
• Audit the ring's GATT server with tools such as bluetoothctl, gatttool, or nRF Connect to confirm whether characteristics accept writes without pairing.
• Correlate anomalous biometric activation events in the vendor cloud with periods when the user was not interacting with the application.

Monitoring Recommendations

• Deploy wireless intrusion detection sensors in environments where employees wear affected rings, and alert on repeated short-lived BLE connections to wearable MAC ranges.
• Track firmware versions across managed wearables and flag any device still running RT09R20_1.00.00_250318.
• Maintain an inventory of personal IoT devices permitted in secure facilities and review it against advisories referencing [CWE-306].

How to Mitigate CVE-2026-89034

Immediate Actions Required

• Restrict use of the affected TCH QRing model in environments where biometric confidentiality matters, including executive protection scenarios and clinical settings.
• Contact the vendor to confirm whether a firmware update supersedes RT09R20_1.00.00_250318 and enforces BLE pairing plus command authorization.
• Instruct users to keep the ring physically inaccessible to untrusted individuals and to disable BLE on paired phones when not in use.

Patch Information

No vendor advisory or patched firmware version is listed in the NVD entry for CVE-2026-89034 at the time of publication. Users should monitor TCH QRing vendor channels for a firmware release that supersedes RT09R20_1.00.00_250318 and implements BLE Secure Connections plus authenticated command handling on the Nordic UART Service.

Workarounds

• Power off the ring when entering areas where BLE eavesdropping is plausible, since the vulnerability requires the device to be advertising and connectable.
• Enforce a policy that prohibits vulnerable wearables from being brought into secure facilities until authenticated firmware is available.
• Where feasible, use BLE jamming or shielded enclosures in high-sensitivity meeting rooms to prevent adjacent-network access to wearables.