CVE-2019-25723: Dräger Perseus A500 DoS Vulnerability

CVE-2019-25723 Overview

CVE-2019-25723 affects the Dräger Perseus A500 anesthesia workstation running software versions 2.00 through 2.02. The device improperly handles non-Medibus-compliant input received through its Medibus interface. An attacker with network access to the interface can send malformed data that overloads the internal processor. The condition triggers a warm restart of the device, dropping ventilation pressure to ambient level and interrupting therapy for several seconds before resumption. The flaw is classified as improper input handling [CWE-1286] and represents a denial of service risk to clinical operations.

Critical Impact

Malformed Medibus traffic can force a warm restart of the Perseus A500, briefly suspending ventilation therapy and dropping airway pressure to ambient level.

Affected Products

• Dräger Perseus A500 software version 2.00
• Dräger Perseus A500 software version 2.01
• Dräger Perseus A500 software version 2.02

Discovery Timeline

• 2026-06-02 - CVE-2019-25723 published to NVD
• 2026-06-03 - Last updated in NVD database

Technical Details for CVE-2019-25723

Vulnerability Analysis

The Perseus A500 exposes a Medibus interface used to exchange device data with external monitoring and information systems. The firmware does not adequately validate inbound frames before routing them to the processing pipeline. When an attacker submits crafted frames that violate Medibus structure, the internal processor consumes excessive resources attempting to interpret the input. The processor enters an overload state and the device performs a warm restart as a protective measure. During the restart window, mechanical ventilation pauses and airway pressure equalizes with ambient air. Therapy resumes automatically after the device reinitializes, but the interruption is clinically significant for patients dependent on continuous ventilation.

Root Cause

The root cause is improper input handling within the Medibus protocol parser. The implementation lacks sufficient bounds and format validation for non-compliant frames. Malformed data is accepted into the processing path rather than being discarded at the protocol boundary, allowing an external attacker to exhaust internal processing capacity.

Attack Vector

Exploitation requires the attacker to deliver crafted data over the Medibus interface. The Medibus channel is typically reached through a connected clinical network or directly attached serial-over-IP gateway. No authentication or user interaction is required. The attacker sends a stream of non-Medibus-compliant data sufficient to overload the processor and force the warm restart sequence.

No public proof-of-concept code has been released for this issue. Technical specifics are limited to the descriptions provided in the Draeger Security Advisory PSA-20-169-01 and the VulnCheck Advisory on Perseus A500 DoS.

Detection Methods for CVE-2019-25723

Indicators of Compromise

• Unexpected warm restart events recorded in the Perseus A500 device log around the time of network activity on the Medibus interface.
• Short ventilation pressure drops to ambient level followed by automatic therapy resumption.
• Bursts of malformed or non-Medibus-compliant frames observed on the clinical serial or serial-over-IP segment connected to the device.

Detection Strategies

• Monitor Medibus traffic for frames that deviate from documented protocol structure, including invalid headers, length fields, or checksum values.
• Correlate device restart events with network packet captures to identify malicious or misconfigured peers.
• Apply network intrusion detection signatures on biomedical VLANs to flag anomalous traffic patterns directed at anesthesia workstations.

Monitoring Recommendations

• Forward Perseus A500 device logs and clinical engineering alerts to a centralized monitoring platform for retention and correlation.
• Track the volume and source of Medibus connections to detect unauthorized devices communicating with the workstation.
• Establish baselines for warm restart frequency and alert on deviations from normal operating behavior.

How to Mitigate CVE-2019-25723

Immediate Actions Required

• Inventory all Perseus A500 devices and identify those running software versions 2.00 through 2.02.
• Restrict access to the Medibus interface to authorized monitoring systems only, using network segmentation and access control lists.
• Coordinate with Dräger service representatives to schedule the software update on affected workstations.

Patch Information

Dräger addressed the issue in a subsequent Perseus A500 software release. Refer to the Draeger Security Advisory PSA-20-169-01 for the vendor's recommended update path and service procedures. Software updates on medical devices must be performed by authorized Dräger service personnel.

Workarounds

• Isolate the Perseus A500 on a dedicated biomedical network segment with strict ingress filtering to the Medibus interface.
• Disconnect the Medibus interface when external data exchange is not clinically required.
• Permit Medibus communication only with validated, known-good monitoring endpoints, blocking all other peers at the network layer.

# Configuration example
# Refer to vendor advisory for authoritative mitigation guidance