---
id: CVE-2026-46033
title: |-
  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 …
summary: |-
  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 …
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H'
cwe:
  - CWE-125
  - CWE-1284
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 4.11, < 5.10.258'
  - 'linux_kernel >= 5.11, < 5.15.209'
  - 'linux_kernel >= 5.16, < 6.1.175'
  - 'linux_kernel >= 6.2, < 6.6.140'
  - 'linux_kernel >= 6.7, < 6.12.86'
  - 'linux_kernel >= 6.13, < 6.18.27'
  - 'linux_kernel >= 6.19, < 7.0.4'
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.4
published: '2026-05-27'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T09:18:06.620'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-46033'
references:
  - url: 'https://git.kernel.org/stable/c/2f31cd1e64a079c845bca31d2da7b3c90a311726'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5db6ef9847717329f12c5ea8aba7e9f588a980c0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/67f1f0933cc3d78dde222842bcad2778ec7a0b88'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/77f59fb2d3aa33e90ec6cbbf45dcfb20ab82b1a9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9aff81e8217e9de2929084b03b3c7f81988c112b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b42821c15445f93daea3e76ada682b2b7181c476'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b69933e97efea238ebbfcf70c2b1be1cd03f13e3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d4c6a6d08e70bb1083c7c405fc7faacbf19aebc0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://access.redhat.com/security/cve/CVE-2026-46033'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2482000'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46033.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
  - cve.org
epss: 0.00131
epssPercentile: 0.03098
ingestedAt: '2026-08-20T20:00:36.678Z'
---

## Overview

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.

## Affected

- `linux_kernel >= 4.11, < 5.10.258`
- `linux_kernel >= 5.11, < 5.15.209`
- `linux_kernel >= 5.16, < 6.1.175`
- `linux_kernel >= 6.2, < 6.6.140`
- `linux_kernel >= 6.7, < 6.12.86`
- `linux_kernel >= 6.13, < 6.18.27`
- `linux_kernel >= 6.19, < 7.0.4`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.4`