CVE-2026-46033

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

crypto: authencesn - reject short ahash digests during instance creation

authencesn requires either a zero authsize or an authsize of at least

4 bytes because the ESN encrypt/decrypt paths always move 4 bytes of

high-order sequence number data at the end of the authenticated data.

While crypto_authenc_esn_setauthsize() already rejects explicit

non-zero authsizes in the range 1..3, crypto_authenc_esn_create()

still copied auth->digestsize into inst->alg.maxauthsize without

validating it. The AEAD core then initialized the tfm's default

authsize from that value.

As a result, selecting an ahash with digest size 1..3, such as

cbcmac(cipher_null), exposed authencesn instances whose default

authsize was invalid even though setauthsize() would have rejected the

same value. AF_ALG could then trigger the ESN tail handling with a

too-short tag and hit an out-of-bounds access.

Reject authencesn instances whose ahash digest size is in the invalid

non-zero range 1..3 so that no tfm can inherit an unsupported default

authsize.