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 affecting the parsing of Digital Imaging and Communications in Medicine (DICOM) files. The flaw allows attackers to execute arbitrary code in the context of the PACS service account. While the advisory states authentication is not required, exploitation requires user interaction to process a malicious DICOM file. The issue was reported through the Zero Day Initiative as ZDI-CAN-25827.

Critical Impact
A crafted DICOM file can trigger memory corruption that results in arbitrary code execution within the MedDream PACS Server service, exposing medical imaging data and connected hospital systems.

Affected Products

MedDream PACS Server (Premium edition)
Component: meddream:pacs_server
DICOM file parsing module

Discovery Timeline

2025-05-22 - CVE-2025-3481 published to the National Vulnerability Database
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. DICOM is the standard format used to store and transmit medical imaging data such as CT, MRI, and X-ray studies. When the parser processes a malformed DICOM file, it copies attacker-controlled data into a fixed-size stack buffer without validating the input length. The resulting stack-based buffer overflow corrupts adjacent stack memory, including the saved return address. An attacker who controls the overflow contents can redirect execution and run arbitrary code in the context of the PACS service account, which typically holds elevated privileges on the imaging server.

Root Cause

The root cause is missing length validation prior to copying user-supplied DICOM data into a fixed-length stack buffer [CWE-121]. The parser trusts size fields and tag values embedded in the DICOM stream rather than enforcing destination buffer bounds. This pattern is common in legacy parsers that rely on memcpy-style operations without preceding length checks.

Attack Vector

Exploitation requires the server to parse a malicious DICOM file. The CVSS vector specifies a local attack vector with required user interaction, meaning an operator or an automated workflow must process the attacker-supplied file. In real environments, DICOM files routinely arrive from modalities, image-sharing portals, and external referrals, expanding the practical attack surface. Successful exploitation yields code execution with the privileges of the PACS service.

No public proof-of-concept exploit code has been released. See the Zero Day Initiative Advisory ZDI-25-245 for technical details from the disclosing researchers.

Detection Methods for CVE-2025-3481

Indicators of Compromise

Unexpected child processes spawned by the MedDream PACS Server service, especially command interpreters such as cmd.exe, powershell.exe, or /bin/sh.
Crashes or restarts of the PACS service correlated with DICOM ingestion events.
DICOM files containing oversized tag values, malformed length fields, or unusually long string-valued elements.
Outbound network connections from the PACS service host to unfamiliar destinations following file ingestion.

Detection Strategies

Monitor process lineage for the MedDream PACS Server process and alert on any non-standard child processes.
Inspect DICOM files at ingestion boundaries using a validating parser to flag length anomalies before they reach the vulnerable parser.
Hunt for stack pivot and shellcode behaviors using behavioral analytics on PACS hosts. The Singularity Endpoint behavioral AI engine can identify exploitation patterns such as anomalous memory execution and unexpected service-to-shell transitions without relying on signatures.

Monitoring Recommendations

Forward PACS host telemetry, including process creation and file write events, into a centralized data lake for correlation. Singularity Data Lake supports OCSF-normalized ingestion for this use case.
Track DICOM ingest volumes and source IPs to detect anomalous submission patterns from external referrers.
Enable crash dump collection on PACS hosts to capture forensic evidence of failed exploitation attempts.

How to Mitigate CVE-2025-3481

Immediate Actions Required

Identify all MedDream PACS Server installations, including Premium edition instances, and inventory their exposure to external DICOM sources.
Restrict DICOM file ingestion to trusted modalities and authenticated peers only.
Apply the vendor-supplied patch referenced in the Zero Day Initiative Advisory ZDI-25-245 as soon as it is available in your environment.
Run the PACS service under a least-privilege account to limit the impact of successful exploitation.

Patch Information

MedDream has been notified through the Zero Day Initiative disclosure process. Administrators should consult MedDream support channels and the ZDI-25-245 advisory for the current fixed version and upgrade guidance. Verify the installed build after patching and confirm that the DICOM parser version reflects the remediated code.

Workarounds

Place the PACS server behind a DICOM gateway or proxy that performs strict schema and length validation before forwarding files.
Segment PACS hosts on an isolated VLAN with strict ingress controls and no direct internet exposure.
Disable or remove any web upload portals that accept DICOM files from unauthenticated users until the patch is applied.
Enable host-based exploit mitigations such as Data Execution Prevention (DEP), Address Space Layout Randomization (ASLR), and Control Flow Guard (CFG) on the PACS host.

bash

# Example: restrict inbound DICOM traffic to known modality subnets on Windows
New-NetFirewallRule -DisplayName "PACS DICOM Allow Modalities" `
  -Direction Inbound -Protocol TCP -LocalPort 104,11112 `
  -RemoteAddress 10.10.20.0/24,10.10.21.0/24 -Action Allow

New-NetFirewallRule -DisplayName "PACS DICOM Block Other" `
  -Direction Inbound -Protocol TCP -LocalPort 104,11112 `
  -Action Block