CVE-2026-44033 in DCMTK
Summary
by MITRE • 10/08/2026
Uncontrolled recursion in XMLNode::ParseXMLElement() and XMLNode::emptyTheNode() in the bundled XML parser (ofstd/libsrc/ofxml.cc) of OFFIS DCMTK 3.7.0 allows an attacker to cause a denial of service (stack exhaustion and process crash) via a crafted XML document with deeply nested elements. The parser is reachable through dcmencap when encapsulating a CDA document, and through any application that calls OFXMLParser::parseFile() or OFXMLParser::parseString() on untrusted input. The issue is fixed in commit d12e350e687530eb41e2b0c860aff4d8c04e5941.
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Analysis
by VulDB Data Team • 10/08/2026
The vulnerability identified involves an uncontrolled recursion flaw within the XML parsing components of the OFFIS DCMTK library, specifically affecting the functions XMLNode::ParseXMLElement and XMLNode::emptyTheNode located in the source file ofstd/libsrc/ofxml.cc. This issue is present in version 3.7.0 of the software suite. The core technical deficiency lies in the parser's inability to limit the depth of nested elements during the parsing process. When an attacker provides a crafted XML document containing deeply nested structures, the recursive nature of these functions causes the application stack to grow exponentially with each level of nesting. This behavior leads directly to stack exhaustion, resulting in a denial of service condition where the affected process crashes due to insufficient memory resources allocated for the call stack.
The operational impact of this vulnerability is significant because it allows remote or local attackers to disrupt services that rely on DCMTK for medical imaging data processing and exchange. The parser functionality is exposed through multiple entry points within the ecosystem, most notably when using dcmencap to encapsulate Clinical Document Architecture documents. Additionally, any application integrating the library can trigger this flaw by invoking OFXMLParser::parseFile or OFXMLParser::parseString methods on untrusted input data. Since medical imaging systems often process external inputs from various sources including other healthcare providers and devices, the ability to crash these services through malformed XML payloads poses a serious risk to system availability and continuity of care operations.
From a classification perspective, this vulnerability aligns with CWE-675, which describes the use of potentially dangerous algorithms or uncontrolled recursion that can lead to resource exhaustion. In terms of offensive security frameworks, it maps to MITRE ATT&CK technique T1499, specifically Endpoint Denial of Service via application layer attacks such as XML bombs or recursive parsing exploits. The attack vector typically involves crafting an XML document with excessive nesting levels rather than relying on complex encoding evasion techniques, making the exploit straightforward but effective against unpatched systems that do not implement depth limits during parsing operations.
Mitigation strategies primarily involve applying the official patch provided by OFFIS DCMTK developers, which is available in commit d12e350e687530eb41e2b0c860aff4d8c04e5941. This update introduces safeguards to limit recursion depth and prevent stack overflow conditions during XML parsing. For organizations unable to immediately upgrade, implementing input validation at the network perimeter or application gateway level can help filter out excessively nested XML structures before they reach the vulnerable parser components. Additionally, configuring operating system-level resource limits such as stack size restrictions may provide a secondary layer of defense by limiting the impact of stack exhaustion attempts, although this is not a substitute for patching the underlying code defect.