CVE-2025-53618: 
Linux Debian vulnerability analysis and mitigation

CVE-2025-53618 is an out-of-bounds read vulnerability in the JPEGBITSCodec::InternalCode functionality of Grassroot DICOM (GDCM) version 3.0.24, a widely used C++ library for processing DICOM medical imaging files. The vulnerability is triggered via the grayscale_convert function when processing a specially crafted DICOM file, leading to an information leak. It was discovered by Emmanuel Tacheau of Cisco Talos, disclosed to the vendor on July 15, 2025, and publicly released on December 16, 2025 (Talos Advisory). The vulnerability carries a CVSS v3.1 base score of 9.1 (Critical) per NVD (AV:N/AC:L/PR:N/UI:N), and 7.4 (High) per Talos (AV:L/AC:H/PR:N/UI:N) (Talos Advisory).

The root cause is classified as CWE-125 (Out-of-bounds Read) and CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). Within JPEGBITSCodec::InternalCode, the input vector is allocated with a fixed length derived from the pixel data size recorded in the DICOM file, but no bounds check is performed at line 286 before computing row_pointer[0] = &image_buffer[cinfo.next_scanline * row_stride]. This out-of-bounds pointer is then passed through jpeg_write_scanlines → process_data_simple_main → pre_process_data → grayscale_convert, where the crash occurs at outptr[col] = inptr[0] (line 495) as inptr advances beyond the allocated buffer. The values controlling iteration (cinfo->image_width, cinfo->input_components, num_rows) are all attacker-controlled via the malicious DICOM file's metadata fields such as PhotometricInterpretation (Talos Advisory).

Successful exploitation results in an out-of-bounds memory read, causing an information leak of potentially sensitive data from process memory and a crash (denial of service via SIGSEGV). The confidentiality impact is high, as arbitrary memory contents adjacent to the image buffer may be exposed, and the availability impact is high due to the application crash. Systems processing DICOM files in medical imaging environments — including PACS servers, radiology workstations, and healthcare applications — are at risk, with potential exposure of sensitive patient data or system memory (Talos Advisory).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time (Talos Advisory). The EPSS score is approximately 0.013% (0.000130), indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. No threat actor attribution has been reported. The vulnerability is detected by Tenable Nessus plugin 278974.

1. Craft a malicious DICOM file: Create a DICOM file with manipulated metadata fields — specifically setting PhotometricInterpretation to MONOCHROME2 (grayscale) and configuring Dimensions, BitsAllocated, BitsStored, and SamplesPerPixel to values that cause the computed row_stride * image_height to exceed the actual pixel data buffer size.
2. Set transfer syntax: Use an uncompressed transfer syntax (e.g., 1.2.840.10008.1.2.1 — Explicit VR Little Endian) so the library attempts JPEG re-encoding via ImageChangeTransferSyntax.
3. Deliver the file: Provide the malicious DICOM file to a target system running GDCM 3.0.24 — this could be via file upload to a PACS server, a shared network directory, or any application that processes DICOM files using the GDCM library.
4. Trigger processing: The application invokes gdcm::ImageChangeTransferSyntax::Change() → TryJPEGCodec() → JPEGBITSCodec::InternalCode(), which sets up the JPEG compression object with attacker-controlled dimensions.
5. Out-of-bounds read occurs: During jpeg_write_scanlines, the row_pointer is computed beyond the allocated buffer boundary. The call chain reaches grayscale_convert, where inptr advances past the buffer end, triggering a SIGSEGV and potentially leaking adjacent memory contents (Talos Advisory).

• Process: Application crash (SIGSEGV) in processes using GDCM 3.0.24, specifically with a backtrace involving grayscale_convert, pre_process_data, process_data_simple_main, gdcmjpeg16_jpeg_write_scanlines, and gdcm::JPEG16Codec::InternalCode.
• Logs: Application crash logs or core dumps referencing jccolor.c at line 295 (grayscale_convert) or line 326 (null_convert); crash reports showing PhotometricInterpretation: MONOCHROME2 or RGB with anomalous dimension values (e.g., 256 x 58112).
• File System: Presence of unexpected or malformed DICOM files with oversized dimension metadata relative to actual pixel data payload; core dump files generated by the GDCM-consuming application.
• Network: Unusual DICOM file submissions (C-STORE operations) to PACS servers containing files with mismatched pixel data sizes and dimension metadata (Talos Advisory).

No official patch has been released for Grassroot DICOM 3.0.24 as of the public disclosure date. Organizations should implement strict input validation and sanitization of DICOM files from untrusted sources, and restrict DICOM file processing to trusted sources only. Network access to systems processing DICOM files should be limited to reduce the remote attack surface. Monitor for application crashes consistent with the described backtrace. Evaluate alternative DICOM libraries or watch the GDCM SourceForge project for patched releases (Talos Advisory).

Cisco Talos published the vulnerability report (TALOS-2025-2210) on December 16, 2025, crediting Emmanuel Tacheau as the discoverer. The disclosure followed a coordinated timeline: vendor notification on July 15, 2025, with multiple follow-ups in August, September, and October before public release. Talos also published a blog post covering this and related vulnerabilities in libbiosig and smallstep/step-ca. RedPacket Security amplified the advisory on social media (Mastodon) shortly after disclosure (Talos Advisory, Talos Blog).