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Blog post · September 11, 2026 · kb.cert.org

CISA: ExLlamaV3 issues update for CUDA bounds-check flaw

Summary

ExLlamaV3 exllamav3_ext contains an out-of-bounds (OOB) memory access issue in its CUDA extension that can result in denial of service or application instability. The vulnerability is tracked as CVE-2026-84286.

The exllamav3_ext module has an OOB memory access vulnerability 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 and causes a CUDA illegal memory access. The root cause is a missing bounds check in the kernel-table dispatch process, where 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.

Primary impacts include denial of service through process crashes and potential unstable execution states within applications utilizing the library.

The vendor addressed the vulnerability in the main repository. Updates are available, and a fix is provided via the merged pull request at https://github.com/turboderp-org/exllamav3/pull/310.

Downstream projects using this library are indirectly exposed, with 49 total dependencies currently tracking the repository. Notable downstream projects directly affected include UnstableLlama / ezexl3 and Ednaordinary / MawDiscord, and developers and maintainers of these dependent repositories are encouraged to rebuild their packages against the patched version of exllamav3_ext.

Our summary. The original keeps its own byline.

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