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CVE-2026-5438

Status: AnalyzedHigh (7.5)—

A gzip decompression bomb vulnerability exists when Orthanc processes HTTP request with `Content-Encoding: gzip`. The server does not enforce limits on decompressed size and allocates memory based on attacker-controlled compression metadata. A specially crafted gzip payload can trigger excessive memory allocation and exhaust system memory.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

AV:N/PR:N/UI:N indica explotación remota sin privilegios (T1190). CWE-770 (asignación excesiva de recursos) y descripción explícita de agotamiento de memoria por gzip bomb = DoS por consumo de recursos (T1499.004).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Filter Network TrafficVulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkApplication Isolation and Sandboxing

Affected technologies (1)

Orthanc-server — Orthanc

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2026-5438",
  "cveTags": [],
  "metrics": {
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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          "id": "CVE-2026-5438",
          "role": "CISA Coordinator",
          "options": [
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              "exploitation": "none"
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              "automatable": "yes"
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              "technicalImpact": "partial"
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          "version": "2.0.3",
          "timestamp": "2026-04-14T15:13:20.018057Z"
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "cret@cert.org",
      "affectedData": [
        {
          "vendor": "Orthanc",
          "product": "DICOM Server",
          "versions": [
            {
              "status": "affected",
              "version": "0",
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              "lessThanOrEqual": "1.12.10"
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  ],
  "published": "2026-04-09T15:16:15.327",
  "references": [
    {
      "url": "https://kb.cert.org/vuls/id/536588",
      "tags": [
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "cret@cert.org"
    },
    {
      "url": "https://www.machinespirits.de/",
      "tags": [
        "Not Applicable"
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      "source": "cret@cert.org"
    },
    {
      "url": "https://www.orthanc-server.com/",
      "tags": [
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      "value": "A gzip decompression bomb vulnerability exists when Orthanc processes HTTP request with `Content-Encoding: gzip`. The server does not enforce limits on decompressed size and allocates memory based on attacker-controlled compression metadata. A specially crafted gzip payload can trigger excessive memory allocation and exhaust system memory."
    }
  ],
  "lastModified": "2026-06-17T10:59:01.503",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:orthanc-server:orthanc:*:*:*:*:*:*:*:*",
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  "sourceIdentifier": "cret@cert.org"
}