CVE-2025-48429: Grassroots DICOM Information Disclosure

CVE-2025-48429 Overview

An out-of-bounds read vulnerability exists in the RLECodec::DecodeByStreams functionality of Grassroot DICOM 3.024. This critical memory corruption flaw allows attackers to craft malicious DICOM files that, when processed, can leak sensitive heap data and potentially cause denial of service conditions. The vulnerability is network-exploitable, requiring no authentication or user interaction, making it particularly dangerous in healthcare environments where DICOM files are commonly exchanged.

Critical Impact

Attackers can exploit this vulnerability to read beyond allocated buffer boundaries, potentially exposing sensitive heap memory contents including patient data, configuration information, or memory structures that could facilitate further attacks. The vulnerability also poses a significant denial of service risk to medical imaging systems.

Affected Products

• Grassroots DICOM (GDCM) version 3.0.24
• Applications and systems using the Malaterre Grassroots DICOM library for DICOM file processing
• Medical imaging software incorporating vulnerable GDCM versions

Discovery Timeline

• 2025-12-16 - CVE CVE-2025-48429 published to NVD
• 2026-01-07 - Last updated in NVD database

Technical Details for CVE-2025-48429

Vulnerability Analysis

This vulnerability is classified under CWE-125 (Out-of-Bounds Read) and CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the RLE (Run-Length Encoding) codec implementation within the Grassroots DICOM library, specifically in the RLECodec::DecodeByStreams function responsible for decompressing RLE-encoded DICOM image data.

When processing a specially crafted DICOM file with malformed RLE-encoded segments, the decoder fails to properly validate boundary conditions before reading from memory buffers. This allows read operations to extend beyond the allocated heap buffer, potentially exposing adjacent memory contents to an attacker who can trigger parsing of a malicious DICOM file.

The network attack vector indicates this vulnerability can be exploited remotely, such as when a vulnerable application processes DICOM files received over a network connection or through file sharing mechanisms common in healthcare environments.

Root Cause

The root cause lies in insufficient bounds checking within the RLE decoding logic of RLECodec::DecodeByStreams. The function processes RLE-encoded pixel data streams but does not adequately verify that read operations remain within the bounds of the allocated input buffer. When encountering maliciously constructed RLE segments that specify read lengths exceeding the actual buffer size, the decoder continues reading beyond the buffer boundary, resulting in an out-of-bounds memory access.

Attack Vector

The attack vector for this vulnerability involves providing a malicious DICOM file to an application using the vulnerable Grassroots DICOM library. The attack flow proceeds as follows:

1. An attacker crafts a DICOM file containing malformed RLE-encoded image data with manipulated segment lengths
2. The malicious file is delivered to a target system through network transfer, email attachment, or file sharing
3. When the target application attempts to decode the DICOM image using RLECodec::DecodeByStreams, the vulnerability triggers
4. The out-of-bounds read operation leaks heap memory contents, which may include sensitive data or be used for information gathering to facilitate further exploitation

For detailed technical information about this vulnerability, see the Talos Intelligence Vulnerability Report.

Detection Methods for CVE-2025-48429

Indicators of Compromise

• Abnormal DICOM file processing errors or application crashes when handling incoming medical imaging files
• Unexpected memory access violations logged by applications using the Grassroots DICOM library
• DICOM files with anomalous RLE segment headers or malformed encoding structures
• Unusual network traffic patterns involving DICOM file transfers from untrusted sources

Detection Strategies

• Implement file integrity monitoring for DICOM files entering the network to detect potentially malicious modifications
• Deploy application-level monitoring to detect crashes or exceptions in DICOM processing workflows
• Configure intrusion detection systems to flag unusual DICOM file structures or RLE encoding anomalies
• Monitor for heap corruption indicators or memory read violations in GDCM-dependent applications

Monitoring Recommendations

• Enable verbose logging for DICOM file processing operations to capture parsing anomalies
• Implement centralized log aggregation for medical imaging systems to correlate potential exploitation attempts
• Deploy endpoint detection and response (EDR) solutions capable of monitoring memory access patterns in healthcare applications
• Establish baseline behavior for DICOM processing workloads to identify deviation indicating potential exploitation

How to Mitigate CVE-2025-48429

Immediate Actions Required

• Identify all systems and applications using Grassroots DICOM version 3.0.24 or earlier vulnerable versions
• Restrict processing of DICOM files from untrusted or unverified sources until patches are applied
• Implement network segmentation to limit exposure of medical imaging systems
• Apply vendor patches as soon as they become available

Patch Information

Organizations should monitor the Grassroots DICOM project for security updates addressing this vulnerability. Review the Talos Intelligence Vulnerability Report for the latest information on available patches and remediation guidance.

Workarounds

• Implement strict input validation for all DICOM files before processing, rejecting files from untrusted sources
• Deploy DICOM file scanning solutions to detect potentially malicious file structures before they reach vulnerable applications
• Consider sandboxing DICOM processing operations to limit the impact of potential memory disclosure
• Temporarily disable RLE decoding functionality if not required for operational needs until patching is complete

# Configuration example - restrict DICOM file sources
# Add to PACS/imaging application firewall rules
# Allow DICOM traffic only from trusted medical device networks
iptables -A INPUT -p tcp --dport 104 -s 192.168.100.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 104 -j DROP

# Log all DICOM processing for audit purposes
# Configure application logging level (example for Linux systems)
export GDCM_LOG_LEVEL=DEBUG