CVE-2025-40019

In the Linux kernel, the following vulnerability has been resolved:

crypto: essiv - Check ssize for decryption and in-place encryption

Move the ssize check to the start in essiv_aead_crypt so that it's also checked for decryption and in-place encryption.

The ESSIV AEAD path failed to validate ssize = assoclen - ivsize for decryption and in-place encryption. A negative ssize could flow into scatterwalk_map_and_copy(), causing out-of-bounds writes/reads of the IV region and kernel crashes or memory corruption. The fix computes ivsize/ssize up front, rejects ssize < 0, and consistently uses these locals across branches, covering decrypt and in-place cases. Privilege required is local (e.g., reachable via kernel crypto consumers or AF_ALG setups), with primary impact on availability and potential integrity compromise. The system is not vulnerable if ESSIV is not in use (i.e. the essiv/aes-cbc-essiv implementation is not present or not being used by any disk/crypto consumer).

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.