dcmjs, a JavaScript library for DICOM manipulation used in web-based medical imaging viewers, contains an input validation bypass in its handling of DS (Decimal String) and IS (Integer String) value representations. The vulnerability allows malformed input strings to bypass sanitization and produce JavaScript Infinity or NaN values, or accept scientific notation in integer fields, violating DICOM standards. This can corrupt spatial geometry, image display, radiation dose calculations, and other clinical data in downstream applications. The issue is fixed in dcmjs version 0.52.0.