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Vulnerability record · CVE-2026-5443 · published 9 April 2026

CVE-2026-5443: Orthanc-server orthanc out-of-bounds write vulnerability

Orthanc Server · Orthanc

A heap buffer overflow vulnerability exists during the decoding of `PALETTE COLOR` DICOM images. Pixel length validation uses 32-bit multiplication for width and height calculations. If these values overflow, the validation check incorrectly succeeds, allowing the decoder to read and write to memory beyond allocated buffers.

9.8 CVSS 3.1 Critical EPSS 0.88% · top 42.7% CWE-787 · Out-of-bounds write
9.8CVSS 3.1 base score
0.88%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References
17 Jun 2026Last modified by NVD

Description

A heap buffer overflow vulnerability exists during the decoding of `PALETTE COLOR` DICOM images. Pixel length validation uses 32-bit multiplication for width and height calculations. If these values overflow, the validation check incorrectly succeeds, allowing the decoder to read and write to memory beyond allocated buffers.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://kb.cert.org/vuls/id/536588 Third Party AdvisoryVDB Entry
https://www.machinespirits.de/ Not Applicable
https://www.orthanc-server.com/ Product

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2026-5442Orthanc-server orthanc out-of-bounds write vulnerabilityA heap buffer overflow vulnerability exists in the DICOM image decoder. Dimension fields are encoded using Value Representation (VR) Unsigned Long (U…EPSS 0.92%9.2CVE-2025-0896Orthanc-server orthanc missing authentication for critical function vulnerabilityOrthanc server prior to version 1.5.8 does not enable basic authentication by default when remote access is enabled. This could result in unauthorize…EPSS 2.5%9.1CVE-2026-5445Orthanc-server orthanc out-of-bounds read vulnerabilityAn out-of-bounds read vulnerability exists in the `DecodeLookupTable` function within `DicomImageDecoder.cpp`. The lookup-table decoding logic used f…EPSS 0.79%8.8CVE-2023-33466Orthanc-server orthanc code injection vulnerabilityOrthanc before 1.12.0 allows authenticated users with access to the Orthanc API to overwrite arbitrary files on the file system, and in specific depl…EPSS 4.2%7.5CVE-2026-5440Orthanc-server orthanc allocation without limits vulnerabilityA memory exhaustion vulnerability exists in the HTTP server due to unbounded use of the `Content-Length` header. The server allocates memory directly…EPSS 0.94%7.5CVE-2026-5437Orthanc-server orthanc out-of-bounds read vulnerabilityAn out-of-bounds read vulnerability exists in `DicomStreamReader` during DICOM meta-header parsing. When processing malformed metadata structures, th…EPSS 0.76%7.5CVE-2026-5438Orthanc-server orthanc allocation without limits vulnerabilityA gzip decompression bomb vulnerability exists when Orthanc processes HTTP request with `Content-Encoding: gzip`. The server does not enforce limits …EPSS 0.76%7.5CVE-2026-5439Orthanc-server orthanc allocation without limits vulnerabilityA memory exhaustion vulnerability exists in ZIP archive processing. Orthanc automatically extracts ZIP archives uploaded to certain endpoints and tru…EPSS 0.76%

Source: NIST National Vulnerability Database (record CVE-2026-5443), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.