CVE-2026-43903: OpenImageIO: SGI RLE decoder heap buffer overflow OIIO_DASSERT bounds checks are no-ops in release builds

OpenImageIO is a toolset for reading, writing, and manipulating image files of any image file format relevant to VFX / animation. Prior to 3.0.18.0 and 3.1.13.0, sgiinput.cpp:265,274 use OIIO_DASSERT for bounds checking in the RLE decode loop. In release builds, OIIO_DASSERT compiles to ((void)sizeof(x)) (dassert.h:210), making all bounds checks no-ops. A crafted .sgi file with RLE count exceeding scanline width causes heap buffer overflow and crash. This vulnerability is fixed in 3.0.18.0 and 3.1.13.0.