The Salsa20 encryption algorithm in the Linux kernel before 4.14.8 does not correctly handle zero-length inputs, allowing a local attacker able to use the AFALG-based skcipher interface (CONFIGCRYPTOUSERAPISKCIPHER) to cause a denial of service (uninitialized-memory free and kernel crash) or have unspecified other impact by executing a crafted sequence of system calls that use the blkcipherwalk API. Both the generic implementation (crypto/salsa20generic.c) and x86 implementation (arch/x86/crypto/salsa20glue.c) of Salsa20 were vulnerable.

The HMAC implementation (crypto/hmac.c) in the Linux kernel before 4.14.8 does not validate that the underlying cryptographic hash algorithm is unkeyed, allowing a local attacker able to use the AFALG-based hash interface (CONFIGCRYPTOUSERAPIHASH) and the SHA-3 hash algorithm (CONFIGCRYPTOSHA3) to cause a kernel stack buffer overflow by executing a crafted sequence of system calls that encounter a missing SHA-3 initialization.