CVE-2026-46033

/// Technical description

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

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References