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.

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.

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.

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.

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.

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.

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.

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.

An out-of-bounds read vulnerability exists in the DecodePsmctRle1 function of DicomImageDecoder.cpp. The PMSCTRLE1 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.

Orthanc server prior to version 1.5.8 does not enable basic authentication by default when remote access is enabled. This could result in unauthorized access by an attacker.

Orthanc versions before 1.12.2 are affected by a reflected cross-site scripting (XSS) vulnerability. The vulnerability was present in the server's error reporting.

A XSS payload can be uploaded as a DICOM study and when a user tries to view the infected study inside the Osimis WebViewer the XSS vulnerability gets triggered. If exploited, the attacker will be able to execute arbitrary JavaScript code inside the victim's browser.

Orthanc before 1.12.0 allows authenticated users with access to the Orthanc API to overwrite arbitrary files on the file system, and in specific deployment scenarios allows the attacker to overwrite the configuration, which can be exploited to trigger Remote Code Execution (RCE).