A heap-buffer-overflow vulnerability exists in the libjxl library within the jxl::N_EMU128::WriteToU8Stage::ProcessRow function. This issue was reported by OSS-Fuzz and involves an out-of-bounds write on the heap during image processing. Multiple versions of libjxl up to and including 0.12.0 are affected. No official patch or remediation information is provided in the available data.