CVE-2026-5442: Orthanc-Server Orthanc

Critical severity, CVSS 9.8. EPSS: 0.9% chance of exploitation in the next 30 days.

A heap buffer overflow vulnerability exists in the DICOM image decoder. Dimension fields are encoded using Value Representation (VR) Unsigned Long (UL), instead of the expected VR Unsigned Short (US), which allows extremely large dimensions to be processed. This causes an integer overflow during frame size calculation and results in out-of-bounds memory access during image decoding.

Affected products

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

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