CVE-2026-5440: Orthanc-Server Orthanc

High severity, CVSS 7.5. EPSS: 0.9% chance of exploitation in the next 30 days.

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.

Affected products

• Orthanc-Server Orthanc: before 1.12.11 (fixed in 1.12.11)

Published 2026-04-09. Last modified 2026-06-17.