Linux Kernel EUVD-2026-49016

Intel's Quick Assist Technology (QAT) driver in the Linux kernel provides hardware-accelerated cryptographic operations including RSA with Chinese Remainder Theorem (CRT) optimization. In qat_rsa_setkey_crt() (drivers/crypto/qat/), DMA-mapped buffers are allocated at key_sz/2 for each of the five CRT components (p, q, dp, dq, qinv). The generic RSA key parser in rsa_helper.c separately validates each component only against the full modulus size n_sz - meaning components up to the full modulus byte length are accepted as structurally valid. The right-alignment code memcpy(dst + half_key_sz - len, src, len) performs an unsigned subtraction: when len > half_key_sz the result wraps to a very large offset, and memcpy writes past (and far before) the allocated buffer. CWE-787 (Out-of-bounds Write) accurately classifies the root cause. The vulnerability was introduced at commit 879f77e9071f (Linux 4.8) when QAT RSA CRT support was first added, and the missing bound check was not caught by the existing !len guard. CPE: cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:*.