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OFFIS DCMTK CVE-2026-44037

| EUVDEUVD-2026-94940 MEDIUM
Uncontrolled Recursion (CWE-674)
2026-10-08 securin GHSA-w8m4-mhcj-8r75
6.8
CVSS 4.0 · Vendor: securin
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Deliver crafted DICOM JSON with deep SQ nesting
  2. Exploit
    Reader recurses through parseDataSet/parseElement/parseSequence
  3. Execution
    Call stack exhausted
  4. Impact
    Parsing process crashes (denial of service)

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Recursion depth limits
Exploitation Conditions

The target must parse an attacker-supplied DICOM JSON document whose SQ (sequence) values are nested beyond the parser's (pre-patch unbounded) recursion depth - specifically a document processed by DcmJSONReader via the json2dcm tool or any service converting untrusted DICOM JSON, such as a DICOMweb ingestion endpoint. Limiting factors: exploitation requires the victim process to actually ingest and parse attacker-controlled JSON (UI:P / local file handling in the base CVSS), and impact is strictly availability - a single process crash with no code execution, data disclosure, or integrity loss. Network reach depends on deployment: a DICOMweb service exposes this remotely, whereas standalone json2dcm use requires delivering a malicious file to the operator.

Impact

This is a genuine but moderate-priority availability issue, not an urgent emergency. All exploitation signals point to low real-world urgency: SSVC reports Exploitation 'none' and Automatable 'no', the CVE is not on CISA KEV, no EPSS score was provided, and no public PoC is referenced - yielding 'no public exploit identified at time of analysis'. The vendor CVSS 4.0 vector (AV:L/AC:L/PR:N/UI:P/VC:N/VI:N/VA:H) confirms the impact is confined to availability (stack exhaustion / process crash) with no confidentiality or integrity effect, consistent with CWE-674 (uncontrolled recursion). A key tension exists in the attack surface: the CVSS vector specifies AV:L (local), matching the named json2dcm command-line tool that parses files locally, yet the description explicitly cites DICOMweb services converting untrusted DICOM JSON - a network-facing scenario that would effectively make this remotely reachable (AV:N) for any PACS/DICOMweb endpoint accepting JSON. Verify your own deployment: if DICOMweb/JSON ingestion is exposed, treat real exposure as higher than the AV:L score implies, though impact remains a crash, not compromise.

Exploit ScenarioDerived

An attacker submits a crafted DICOM JSON document containing deeply nested sequence (SQ) values to a target that parses it - either via the json2dcm CLI tool or a DICOMweb service that converts untrusted JSON payloads. The malicious nesting drives unbounded mutual recursion through parseDataSet/parseElement/parseSequence, exhausting the stack and crashing the process. No public exploit is identified at time of analysis, but the crafted-input requirement is trivial to construct.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 08, 2026

Stack exhaustion denial of service in OFFIS DCMTK 3.7.0 lets an attacker crash a JSON-parsing process by supplying a crafted DICOM JSON document whose sequence (SQ) values are nested deeply enough to exhaust the call stack through uncontrolled mutual recursion in DcmJSONReader (parseDataSet, parseElement and parseSequence in dcmdata/libsrc/dcjsonrd.cc). The affected components are the json2dcm conversion tool and any service that converts untrusted DICOM JSON, such as DICOMweb ingestion endpoints, with impact limited to availability (process crash) and no code execution, disclosure or integrity loss. No public exploit identified at time of analysis and CISA's SSVC records Exploitation: none, but the flaw is trivially automatable by anyone who can deliver a malicious JSON payload; it is fixed upstream in commit cf955e64c35a1e07ba10698f639d5dcdec53b9d7, which caps sequence nesting at 128 levels.

RemediationAI

Apply the upstream fix, either by cherry-picking or upgrading to a build containing commit cf955e64c35a1e07ba10698f639d5dcdec53b9d7, which introduces DCMJSON_MAX_SEQUENCE_NESTING 128 and returns EC_NestingDepthLimitExceeded for deeper documents; because no tagged release version is confirmed in the supplied data, treat this as an upstream commit fix and verify a vendor release rather than assuming a specific 3.7.x build ships it. Consult the vendor issue at https://support.dcmtk.org/redmine/issues/1225 and the commit diff at https://github.com/DCMTK/dcmtk/commit/cf955e64c35a1e07ba10698f639d5dcdec53b9d7 for integration guidance. If patching is delayed, pre-validate or reject DICOM JSON before it reaches DcmJSONReader by counting nested "SQ" objects and refusing anything beyond a conservative depth (128 or lower), either in the web front end, API gateway, or a shim around json2dcm; legitimate studies with deeply nested functional groups may be rejected, so log and quarantine rather than silently dropping. Run json2dcm and any conversion worker in a low-privilege, sandboxed process with constrained address space and stack (for example ulimit -s and cgroup memory limits), and configure automatic restart with payload-quarantine alerting so a crash becomes an observable, contained event rather than an outage. On DICOMweb deployments, enforce payload size and schema limits at the HTTP layer and restrict ingestion endpoints to authenticated, rate-limited clients; these are compensating controls only and do not remove the underlying recursion defect, which is why the upstream depth-limit patch remains the primary remediation.

Affected VersionsENISA

DCMTK 3.7.0

Affected Packages

euvd dcmtk no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

DICOM JSON is the JSON serialization of DICOM data elements used to exchange studies over DICOMweb and by conversion utilities such as json2dcm. Sequence (SQ) elements may legally contain nested datasets, and DcmJSONReader parses them with three mutually recursive routines: parseDataSet() iterates elements, parseElement() dispatches sequence values, and parseSequence() recurses back into parseDataSet() for each item. Before the fix, no depth counter or nesting limit existed (CWE-674, uncontrolled recursion), so each additional SQ level added stack frames until the thread's stack was exhausted and the process aborted. The upstream patch in dcmdata/include/dcmtk/dcmdata/dcjsonrd.h and dcmdata/libsrc/dcjsonrd.cc threads a size_t depth parameter through all three functions, defines DCMJSON_MAX_SEQUENCE_NESTING 128, and returns EC_NestingDepthLimitExceeded with a DCMDATA_ERROR message when depth exceeds that value; recursion is started at depth 0 from readAndConvertJSONFile(). The CPE entry cpe:2.3:a:offis:dcmtk:*:*:*:*:*:*:*:* identifies DCMTK broadly, with EUVD narrowing the affected release to 3.7.0; the vulnerable code lives in the dcmdata library rather than in a standalone binary, so any application linking DCMTK's JSON reader inherits the weakness. Note the scoring discrepancy between the CVE record (CVSS 4.0 AV:L/PR:N/UI:P, VA:H) and the independent assessment (CVSS 3.1 AV:L/AC:L/PR:N/UI:R, A:H), which agree that availability is the only impacted security property.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (securin) PRIMARY 6.8 MEDIUM
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
vuln.today AI 5.5 MEDIUM

Primary vector is local file parsing (json2dcm) requiring the operator to process a crafted file (UI:R), no privileges needed, and impact is availability-only; AV:N would apply if exposed via DICOMweb.

3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.0 AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Red Hat 5.5 MEDIUM

Primary rating from Vendor (securin).

CVSS VectorVendor: securin

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Passive
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
None
Vulnerable system: Availability
High
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

Uncontrolled mutual recursion between DcmJSONReader::parseDataSet(), DcmJSONReader::parseElement() and DcmJSONReader::parseSequence() in dcmdata/libsrc/dcjsonrd.cc of OFFIS DCMTK 3.7.0 allows an attacker to cause a denial of service (stack exhaustion and process crash) via a crafted DICOM JSON document with deeply nested sequence (SQ) values. The json2dcm tool and any service that converts untrusted DICOM JSON (for example, DICOMweb payloads) with this reader are affected. The issue is fixed in commit cf955e64c35a1e07ba10698f639d5dcdec53b9d7.

Threat Intelligence Overview

EPSS Score
0.1%
Top 99% exploitable
Prevalence
Medium
de facto open-source DICOM toolkit, widespread in medical imaging software
Data Quality
5 sources
Confidence: Medium
EUVD NVD CVE.org EPSS Vulnrichment Vendor GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +34
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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Vendor StatusVendor

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