Heap Buffer Overflow in llama.cpp by Cyera

CVE-2026-43629

What is CVE-2026-43629?

The vulnerability in llama.cpp introduces a heap buffer overflow in the KV cache state restore path. Specifically, the state_read_data() function computes the write size without adequate overflow checks. This flaw permits unauthorized attackers, equipped with write access to the slot_save_path directory, to corrupt the heap memory. By crafting specially designed state files, attackers can manipulate the cell_count multiplication, causing it to overflow or exceed the predefined tensor buffer allocation. This exploitation can lead to the writing of attacker-controlled bytes beyond buffer limits, which may potentially corrupt heap metadata, compromise model weights, or enable arbitrary code execution through function pointer modifications.

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