CVE-2026-5442 Heap Buffer Overflow in DICOM Image Decoder via VR UL Dimensions
An attacker can trigger a heap buffer overflow in the DICOM decoder via malformed dimensions, potentially leading to code execution or service disruption.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-5442?
CVE-2026-5442 is a critical vulnerability in Orthanc DICOM Server, published on 9 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-787
Which versions are affected by CVE-2026-5442?
It affects 1 product.
Products include Orthanc-Server Orthanc.
How do I fix CVE-2026-5442?
Apply the vendor's patch.
Is CVE-2026-5442 being exploited?
There is no known exploitation of CVE-2026-5442 in the wild and no public exploit code.
Other vulnerabilities in Orthanc DICOM Server
- CVE-2026-5443 Heap Buffer Overflow in DICOM Image Decoder (Palette Color Decode)
- CVE-2025-0896 Orthanc Server Missing Authentication for Critical Function
- CVE-2026-5445 Out-of-Bounds Read in DicomImageDecoder (DecodeLookupTable)
- CVE-2023-33466 Path traversal in n/a
- CVE-2026-5437 Out-of-Bounds Read in DicomStreamReader
Sources
Also known as DEBIAN-CVE-2026-5442, GHSA-f2m7-r4gw-p642, UBUNTU-CVE-2026-5442.