CVE-2026-44034: Heap out-of-bounds read in DCMTK RLE decodeFrame()
A heap-based out-of-bounds read in DcmRLECodecDecoder::decodeFrame() in dcmdata/libsrc/dcrleccd.cc of OFFIS DCMTK 3.7.0 allows an attacker to read up to 63 bytes of adjacent heap memory, or cause a crash, via a crafted RLE Lossless DICOM file whose pixel data fragment is shorter than the 64-byte RLE header. The function copies 64 bytes without checking the fragment length, a check that the sibling function decode() already performs. Applications that decode RLE images frame by frame (for example, through DcmPixelData::getUncompressedFrame()) are affected. The dcmdrle command-line tool uses decode() and is not affected. The issue is fixed in commit 45469f3c30037e9c7159290e4bb74cd7b3b9ef1d.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
OFFIS DCMTKto a version that resolves this vulnerability.Patch 45469f3c30037e9c7159290e4bb74cd7b3b9ef1d
Event History
Frequently Asked Questions
Which DCMTK usage paths are affected?
Applications that decode RLE images frame by frame, such as through DcmPixelData::getUncompressedFrame(), are affected. The dcmdrle command-line tool is not affected because it uses decode(), which already checks the RLE header length.
What does an attacker need to provide to trigger the issue?
An attacker needs to cause the application to process a crafted RLE Lossless DICOM file with a pixel data fragment shorter than the required 64-byte RLE header. The vulnerable decodeFrame() path then copies 64 bytes without validating the fragment length.
What can happen if exploitation succeeds?
The flaw can read up to 63 bytes of adjacent heap memory or cause the application to crash. Exploitation requires user interaction according to the provided vector.
What should teams do if they use the affected frame-by-frame decoding path?
Update to a DCMTK build that includes commit 45469f3c30037e9c7159290e4bb74cd7b3b9ef1d. If updating is not immediately possible, avoid processing untrusted RLE Lossless DICOM files through frame-by-frame decoding paths.