CVE-2025-3481: MedDream PACS Server RCE Vulnerability

CVE-2025-3481 Overview

CVE-2025-3481 is a stack-based buffer overflow [CWE-121] in MedDream PACS Server that enables arbitrary code execution through malicious DICOM file parsing. The flaw exists in the routine that copies user-supplied data into a fixed-length stack buffer without validating its length. Successful exploitation grants code execution in the context of the PACS service account. The issue was reported through the Zero Day Initiative as ZDI-CAN-25827 and disclosed publicly as ZDI-25-245. While the CVSS attack vector is local, the trigger is a crafted DICOM file, meaning any workflow that ingests untrusted imaging studies can deliver the payload.

Critical Impact

Remote attackers can execute arbitrary code on MedDream PACS Server installations by delivering a malicious DICOM file, compromising medical imaging infrastructure and patient data.

Affected Products

• MedDream PACS Server (Premium edition)
• Installations parsing DICOM files prior to the vendor patch
• Healthcare environments accepting external DICOM uploads

Discovery Timeline

• 2025-05-22 - CVE-2025-3481 published to NVD
• 2025-07-11 - Last updated in NVD database

Technical Details for CVE-2025-3481

Vulnerability Analysis

The vulnerability resides in the DICOM file parser of MedDream PACS Server. Digital Imaging and Communications in Medicine (DICOM) is the standard format for medical imaging data. When the server processes a DICOM file, it reads attacker-controlled fields and copies them into a stack-allocated buffer of fixed size. The parser does not verify that the source length fits the destination buffer before performing the copy.

An attacker who can place or transmit a crafted DICOM file to the server triggers a stack buffer overflow during parsing. The overflow corrupts adjacent stack memory, including saved return addresses and structured exception handlers. Successful exploitation yields arbitrary code execution under the service account that runs the PACS process. In typical deployments this account has broad access to imaging archives, study databases, and integrated hospital systems.

Root Cause

The root cause is missing bounds validation [CWE-121] prior to a memory copy operation on user-controlled DICOM tag data. The parser trusts length or terminator values present in the file and writes past the end of a fixed-size stack buffer.

Attack Vector

Exploitation requires the target server to parse the malicious DICOM file. Delivery paths include DICOM upload endpoints, file shares monitored by the PACS, and any modality or workstation that routes studies to the server. User interaction is required to process the file, as reflected in the CVSS vector. Refer to the Zero Day Initiative Advisory ZDI-25-245 for technical specifics.

// No verified proof-of-concept code is publicly available.
// See ZDI-25-245 for vendor and researcher technical details.

Detection Methods for CVE-2025-3481

Indicators of Compromise

• Unexpected crashes or restarts of the MedDream PACS Server process during DICOM ingestion
• DICOM files containing oversized tag values that exceed standard field length expectations
• Child processes spawned by the PACS service account, particularly command interpreters or scripting engines
• Outbound network connections initiated by the PACS service to non-imaging endpoints

Detection Strategies

• Inspect inbound DICOM files for malformed or excessively long attribute values prior to ingestion
• Monitor the PACS service process for memory access violations and abnormal termination events
• Hunt for anomalous process trees originating from the MedDream service binary
• Correlate Windows Error Reporting and application crash logs with DICOM upload activity

Monitoring Recommendations

• Enable verbose logging on DICOM receive endpoints and retain files for forensic review
• Forward PACS host telemetry, including process creation and module load events, to a centralized analytics platform
• Alert on first-time binaries or scripts executed by the PACS service account

How to Mitigate CVE-2025-3481

Immediate Actions Required

• Restrict DICOM ingestion to authenticated peers on trusted network segments only
• Apply the vendor-supplied patch from MedDream as soon as it is available
• Run the PACS service under a least-privilege account with no interactive logon rights
• Isolate the PACS host from general-purpose user workstations and the public internet

Patch Information

Consult the Zero Day Initiative Advisory ZDI-25-245 and the MedDream vendor support channel for the fixed release of PACS Server Premium. Update all instances of the server, including failover and disaster recovery nodes.

Workarounds

• Place a DICOM-aware proxy or gateway in front of the PACS to validate file structure before forwarding
• Disable any unauthenticated DICOM listeners and enforce TLS with peer certificate validation
• Apply host-based exploit mitigations such as Data Execution Prevention and Control Flow Guard on the PACS host

# Example: restrict DICOM port 104 to known modality IPs on Windows
netsh advfirewall firewall add rule name="PACS-DICOM-Allowlist" \
  dir=in action=allow protocol=TCP localport=104 \
  remoteip=10.0.0.10,10.0.0.11,10.0.0.12
netsh advfirewall firewall add rule name="PACS-DICOM-DenyAll" \
  dir=in action=block protocol=TCP localport=104