CVE-2026-5439: Orthanc-Server Orthanc

High severity, CVSS 7.5. EPSS: 0.8% chance of exploitation in the next 30 days.

A memory exhaustion vulnerability exists in ZIP archive processing. Orthanc automatically extracts ZIP archives uploaded to certain endpoints and trusts metadata fields describing the uncompressed size of archived files. An attacker can craft a small ZIP archive containing a forged size value, causing the server to allocate extremely large buffers during extraction.

Affected products

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

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