VU#369611: ExLlamaV3 contains Denial of Service vulnerability via insufficient bounds checking on kernel dispatch index
Brief
Overview
An out-of-bounds (OOB) memory access vulnerability involving unchecked array indexing has been identified in the exllamav3_ext compute unified device architecture ( CUDA ) extension. Successful exploitation can lead to an immediate denial of service or application instability. This vulnerability is tracked as CVE-2026-84286.
Description
An OOB memory access vulnerability exists in the exllamav3_ext module due to insufficient input validation.
When the kernel parameter K is set to 0 in a crafted input, the extension generates a negative array index, resulting in a CUDA illegal memory access. s. The root cause is a missing bounds check in the kernel-table dispatch process. The checkpoint-derived block index ( cbi ) is used to access a fixed 24-entry array without confirming that either K or cbi fall within safe limits.