CVE-2026-87020

Orthanc DICOM Server Integer Overflow or Wraparound

An integer overflow in a specified pitch and buffer-size computation leads to a heap out-of-bounds write when Orthanc DICOM Server decodes an attacker-supplied PNG.

CVSS 4.0 · 7.2 High EPSS < 1% KEV · Not listed

Vendors

Orthanc

Products

Dicom Server

CVE-2026-10528

Orthanc DICOM Server DCMTK FromDcmtkBridge.cpp read stack-based overflow

A security flaw has been discovered in Orthanc DICOM Server up to 1.12.11. This issue affects the function DcmItem::read of the file OrthancFramework/Sources/DicomParsing/FromDcmtkBridge.cpp of the component DCMTK Parser. Performing a manipulation results in stack-based buffer overflow. Attacking locally is a requirement. The exploit has been released to the public and may be used for attacks. The patch is named bae99026ca97. To fix this issue, it is recommended to deploy a patch.

CVSS 4.0 · 4.8 Medium EPSS < 1% KEV · Not listed

Vendors

Orthanc

Products

Dicom Server

CVE-2026-10173

Orthanc Explorer 2 URL StudyList.vue cross site scripting

A weakness has been identified in Orthanc Explorer 2 up to 1.12.0. The impacted element is an unknown function of the file WebApplication/src/components/StudyList.vue of the component URL Handler. This manipulation of the argument remote-source causes cross site scripting. It is possible to initiate the attack remotely. The exploit has been made available to the public and could be used for attacks. Patch name: 21f78ce5da668bf5233efcd1896ec7c6e3b22eae. Applying a patch is the recommended action to fix this issue.

CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Orthanc

Products

Explorer 2

CVE-2026-5439

Memory Exhaustion via Forged ZIP Metadata

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.

CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

Vendors

Orthanc Orthanc-server

Products

Dicom Server Orthanc

CVE-2026-5437

Out-of-Bounds Read in DicomStreamReader

An out-of-bounds read vulnerability exists in `DicomStreamReader` during DICOM meta-header parsing. When processing malformed metadata structures, the parser may read beyond the bounds of the allocated metadata buffer. Although this issue does not typically crash the server or expose data directly to the attacker, it reflects insufficient input validation in the parsing logic.

CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

Vendors

Orthanc Orthanc-server

Products

Dicom Server Orthanc

CVE-2026-5441

Out-of-Bounds Read in DicomImageDecoder (PMSCT_RLE1 Decompression)

An out-of-bounds read vulnerability exists in the `DecodePsmctRle1` function of `DicomImageDecoder.cpp`. The `PMSCT_RLE1` decompression routine, which decodes the proprietary Philips Compression format, does not properly validate escape markers placed near the end of the compressed data stream. A crafted sequence at the end of the buffer can cause the decoder to read beyond the allocated memory region and leak heap data into the rendered image output.

CVSS 3.1 · 7.1 High EPSS < 1% KEV · Not listed

Vendors

Orthanc Orthanc-server

Products

Dicom Server Orthanc

CVE-2026-5444

Heap Buffer Overflow in PAM Image Buffer Allocation

A heap buffer overflow vulnerability exists in the PAM image parsing logic. When Orthanc processes a crafted PAM image embedded in a DICOM file, image dimensions are multiplied using 32-bit unsigned arithmetic. Specially chosen values can cause an integer overflow during buffer size calculation, resulting in the allocation of a small buffer followed by a much larger write operation during pixel processing.

CVSS 3.1 · 7.1 High EPSS < 1% KEV · Not listed

Vendors

Orthanc Orthanc-server

Products

Dicom Server Orthanc

CVE-2026-5442

Heap Buffer Overflow in DICOM Image Decoder via VR UL Dimensions

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.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed

Vendors

Orthanc Orthanc-server

Products

Dicom Server Orthanc

CVE-2026-5438

Gzip Decompression Bomb via Content-Encoding Header

A gzip decompression bomb vulnerability exists when Orthanc processes HTTP request with `Content-Encoding: gzip`. The server does not enforce limits on decompressed size and allocates memory based on attacker-controlled compression metadata. A specially crafted gzip payload can trigger excessive memory allocation and exhaust system memory.

CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

Vendors

Orthanc Orthanc-server

Products

Dicom Server Orthanc

CVE-2026-5445

Out-of-Bounds Read in DicomImageDecoder (DecodeLookupTable)

An out-of-bounds read vulnerability exists in the `DecodeLookupTable` function within `DicomImageDecoder.cpp`. The lookup-table decoding logic used for `PALETTE COLOR` images does not validate pixel indices against the lookup table size. Crafted images containing indices larger than the palette size cause the decoder to read beyond allocated lookup table memory and expose heap contents in the output image.

CVSS 3.1 · 9.1 Critical EPSS < 1% KEV · Not listed

Vendors

Orthanc Orthanc-server

Products

Dicom Server Orthanc

CVE-2026-5443

Heap Buffer Overflow in DICOM Image Decoder (Palette Color Decode)

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 · 9.8 Critical EPSS < 1% KEV · Not listed

Vendors

Orthanc Orthanc-server

Products

Dicom Server Orthanc

CVE-2026-5440

Memory Exhaustion via Unbounded Content-Length

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.

CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

Vendors

Orthanc Orthanc-server

Products

Dicom Server Orthanc