CVE-2026-66098: Mira Hormone Monitor DoS Vulnerability

CVE-2026-66098 Overview

CVE-2026-66098 affects the Mira hormone monitor device firmware. The firmware accepts a 0x01 write from any Bluetooth Low Energy (BLE) central without authentication. This write causes the device to reboot into bootloader mode. An attacker within BLE range can trigger a denial-of-service condition and disrupt ovulation tracking and fertility monitoring workflows. The weakness is classified as Missing Authentication for Critical Function [CWE-306].

Critical Impact
Any unauthenticated BLE peer within radio range can force the Mira hormone monitor into bootloader mode, halting fertility tracking and creating a persistent availability impact on the medical device.

Affected Products

Mira hormone monitor device firmware (as identified in CISA Medical Advisory ICSMA-26-223-01)

Discovery Timeline

2026-08-11 - CVE-2026-66098 published to the National Vulnerability Database (NVD)
2026-08-12 - Last updated in NVD database

Technical Details for CVE-2026-66098

Vulnerability Analysis

The Mira hormone monitor exposes a BLE Generic Attribute Profile (GATT) characteristic that lacks authentication controls. When any BLE central writes the byte value 0x01 to this characteristic, the firmware immediately transitions the device into its bootloader mode. Bootloader mode interrupts normal operation and prevents the device from performing hormone measurements or communicating results to the paired mobile application. The condition persists until the device is manually recovered or reflashed, extending the operational impact beyond a transient disruption.

Root Cause

The root cause is Missing Authentication for Critical Function [CWE-306]. The firmware treats the bootloader-transition write as a trusted operation without verifying pairing, bonding, or a command-specific authentication token. Any BLE peer that can discover the service and characteristic can therefore issue the reboot command. The design does not enforce BLE Security Mode 1 Level 2 or higher for the affected characteristic, and no application-layer verification gates the state change.

Attack Vector

Exploitation requires adjacent-network access over BLE. An attacker within Bluetooth range scans for the device, connects as a central, enumerates GATT services, and writes 0x01 to the vulnerable characteristic. No user interaction, credentials, or prior pairing are required. The result is an availability loss on the medical device that supports fertility monitoring workflows. See the CISA Medical Advisory ICSMA-26-223-01 and the GitHub CSAF White Paper for coordinated disclosure details.

No public proof-of-concept code is available. The vulnerability is described in prose only, consistent with the vendor advisory content.

Detection Methods for CVE-2026-66098

Indicators of Compromise

Unexpected transitions of the Mira hormone monitor into bootloader mode outside of firmware update windows.
Loss of BLE connectivity between the Mira device and its paired mobile application without a user-initiated action.
Gaps or missing samples in ovulation tracking data that correlate with time periods when unknown BLE devices were nearby.

Detection Strategies

Monitor BLE traffic in clinical or home-use environments for unsolicited GATT write operations targeting the Mira device from unknown central addresses.
Correlate device-side telemetry, when available, with mobile application logs to identify repeated forced reboots.
Use Bluetooth sniffing hardware in high-value environments to capture write requests carrying the 0x01 payload against the affected characteristic.

Monitoring Recommendations

Track physical proximity of unknown BLE peripherals in areas where the device is used, particularly in shared or public spaces.
Log every entry into bootloader mode reported by the paired application and alert on frequencies inconsistent with normal firmware update cadence.
Review the CISA Medical Advisory ICSMA-26-223-01 for vendor-provided detection updates and follow subsequent CSAF revisions.

How to Mitigate CVE-2026-66098

Immediate Actions Required

Limit use of the Mira hormone monitor to trusted physical environments where unknown BLE devices are unlikely to be within range.
Power down or disable BLE on the device when not actively taking a measurement to reduce exposure.
Contact the device vendor for firmware updates that add authentication to the bootloader-transition characteristic.

Patch Information

No patch identifier is listed in the enriched CVE data. Refer to the CISA Medical Advisory ICSMA-26-223-01 and the associated CSAF advisory document for the current remediation status and any subsequent firmware releases from the vendor.

Workarounds

Operate the device only in physically controlled locations to reduce the population of potential BLE attackers.
Keep the device paired with a single known mobile host and disconnect promptly after each measurement session.
Document any unexpected bootloader-mode events and report them to the vendor and to the CISA medical advisory contact listed in ICSMA-26-223-01.

bash

# No vendor-supplied configuration hardening command is published for this CVE.
# Refer to CISA Medical Advisory ICSMA-26-223-01 for updated guidance.