CISA Flags Critical Flaw in Grassroots DICOM Imaging Library

The U.S. federal government is warning of a high severity in an open-source library commonly used for medical imaging products that could allow an attacker to crash hospital imaging systems. There is no patch.

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DICOM – Digital Imaging and Communications in Medicine – is an international standard implemented most radiology, cardiology imaging, and radiotherapy devices for storing and retrieving medical image information.

The DICOM standard is a widely used, said Himaja Motheram, security researcher at security firm Censys. “It’s been around forever, since the early 2000s and has significant GitHub activity and academic citations.

The Grassroots DICOM library – the subject of the U.S. alert – ships by default with a number of other popular image processing tools. Many organizations probably use it through another tool and don’t even realize it,” she said.

The DICOM standard itself is a legacy protocol from the 1980s that is insecure by default in many ways. “The format admits executable code, no authentication or encryption, no integrity checking of the file contents by default,” she said.

“It was designed for maximum reliability and interoperability in clinical environments, not maximum data security,” Motheram said.

An advisory published Tuesday by the U.S. Cybersecurity Infrastructure and Security Agency identified the Grassroots DICOM library flaw as a “missing release of memory after effective lifetime” vulnerability. The problem affects GDCM version 3.2.2.

The flaw is exploitable remotely, requires no authentication and has high availability impact, said Mykyta Mudryi, co-founder of ARIMLABS, the security firm that identified and reported the vulnerability to CISA.

“In practice, an attacker could crash PACS servers – taking an entire hospital’s imaging archive offline, freeze diagnostic workstations mid-read – potentially during time-sensitive emergency imaging, or exhaust server memory across a network by sending multiple malicious files,” Mudryi told Information Security Media Group, referring to picture archiving and communication systems.

The vulnerability spotlights a problem frequently found in medical imaging products, said Axel Wirth, chief security strategist at medical device cybersecurity firm MedCrypt.

“Any imaging or PACS type device has a high degree of software complexity and with that comes the potential for more vulnerabilities, including those introduced by the supply chain,” he said. “We also know that imaging systems have a long useful life and certainly contribute to the legacy inventory problem at hospitals,” he said.

“These legacy systems are, in a sense, the lowest common demonstrator and may result in hospitals implementing older versions of DICOM protocols instead of newer, more secure and encrypted versions.”

Small Attack File, Big Effect

The vulnerability, CVE-2026-3650, has a base score of 7.5. “A memory leak exists in the Grassroots DICOM library,” CISA said. A small file of just roughly 150 bytes could cause the system to allocate up to 4.2 gigabytes of memory and not release it.

“The DoS attack can also be used as smokescreen – disrupting imaging systems to divert attention while a more targeted intrusion occurs elsewhere on the hospital network,” Mudryi warned

GDMC’s reach “is far broader than its modest open-source profile might suggest, because it functions as a foundational dependency embedded inside many larger software platforms,” he added. Several major medical imaging vendors are affected.

“In practical terms, GDCM’s code likely runs on thousands of clinical and research systems worldwide – often without the end-user or even the system administrator being aware of its presence,” he said.

“Critically, GDCM is bundled as a core component inside the Insight Toolkit, which is one of the most widely used medical image processing frameworks in the world. ITK’s latest releases still ship with GDCM 3.2.2 as a dependency,” he said. GDCM code flows through ITK into products including 3D Slicer, SimpleITK, the Medical Imaging Interaction Toolkit. “Orthanc, a widely deployed open-source DICOM server, also offers an official GDCM plugin used as a decoder/transcoder for JPEG 2000 and other compressed transfer syntaxes,” he said.

Hospitals and radiology departments use software built on GDCM to run PACS servers, imaging workstations and DICOM viewers – the tools radiologists and technologists use daily to view imaging and ultrasound studies, he said. GDCM supports the creation of image viewers, PACS systems and research-oriented tools in healthcare.

Research institutions use GDCM-dependent tools like 3D Slicer for surgical planning, volumetric analysis and medical image segmentation.

“Dental and orthopedic companies like Dentsply Sirona and Zimmer Biomet may use it within their proprietary imaging and implant-planning software. Clinicians themselves rarely interact with GDCM directly – they interact with applications that silently depend on it to parse and decode the DICOM files produced by scanners and imaging equipment,” Mudryi said.

No Patch Available

CISA said Grassroots DICOM has not responded to requests to work with the agency to mitigate the flaw. CISA recommends users to refer to update information about the software on SourceForge.

Given that no patch is available for the latest vulnerability, organizations should take a layered defensive approach, Mudryi suggested.

“First, network isolation is critical. DICOM servers and imaging workstations should not be directly accessible from the internet or from general business networks,” he said. CISA recommends locating control system devices behind firewalls and isolating them from business networks.

“Second, organizations should implement DICOM file validation at the network perimeter,” he said. “Proxy or gateway solutions that inspect incoming DICOM files for malformed metadata before they reach PACS servers or workstations can serve as a front-line filter. Files with invalid or non-standard VR types in File Meta Information – the specific trigger for this vulnerability – could be flagged or rejected.”

Third, resource limits should be configured on systems running GDCM-dependent software, he recommended. “Operating-system-level controls like cgroups on Linux, or process memory limits, can prevent a single parsing operation from consuming all available system memory, converting a potential system crash into a contained process failure.”

Finally, incident response plans should be updated to account for the possibility of imaging system disruption, including fallback procedures for accessing images during an outage, he said.

Grassroots DICOM has been the subject of at least one other previous CISA vulnerability advisory last December concerning an “out-of-bounds write” flaw. If exploited, CISA said the vulnerability could also allow an attacker to craft a malicious DICOM file, if opened, could crash the application resulting in a denial-of-service condition. A patch is available in version 3.2.2, the same version that contains the latest flaw.