---
id: CVE-2025-40204
title: 'sctp: Fix MAC comparison to be constant-time'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  sctp: Fix MAC comparison to be constant-time

  To prevent timing attacks, MACs need to be compared in constant time.
  Use the appropriate helper function for this.
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    b93fa8dc521d00d2d44bf034fb90e0d79b036617
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    0e8b8c326c2a6de4d837b1bb034ea704f4690d77
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    1cd60e0d0fb8f0e62ec4499138afce6342dc9d4c
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    9c05d44ec24126fc283835b68f82dba3ae985209
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    ed3044b9c810c5c24eb2830053fbfe5fd134c5d4
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    8019b3699289fce3f10b63f98601db97b8d105b0
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    0b32ff285ff6f6f1ac1d9495787ccce8837d6405
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    dd91c79e4f58fbe2898dac84858033700e0e99fb
  - Linux 2.6.12
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-15T21:58:06.126976Z'
published: '2025-11-12'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:02:40.705Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-40204'
references:
  - url: 'https://git.kernel.org/stable/c/b93fa8dc521d00d2d44bf034fb90e0d79b036617'
  - url: 'https://git.kernel.org/stable/c/0e8b8c326c2a6de4d837b1bb034ea704f4690d77'
  - url: 'https://git.kernel.org/stable/c/1cd60e0d0fb8f0e62ec4499138afce6342dc9d4c'
  - url: 'https://git.kernel.org/stable/c/9c05d44ec24126fc283835b68f82dba3ae985209'
  - url: 'https://git.kernel.org/stable/c/ed3044b9c810c5c24eb2830053fbfe5fd134c5d4'
  - url: 'https://git.kernel.org/stable/c/8019b3699289fce3f10b63f98601db97b8d105b0'
  - url: 'https://git.kernel.org/stable/c/0b32ff285ff6f6f1ac1d9495787ccce8837d6405'
  - url: 'https://git.kernel.org/stable/c/dd91c79e4f58fbe2898dac84858033700e0e99fb'
tags:
  - cve.org
epss: 0.00463
epssPercentile: 0.38596
ingestedAt: '2026-10-15T22:48:25.551Z'
---

## Overview

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

sctp: Fix MAC comparison to be constant-time

To prevent timing attacks, MACs need to be compared in constant time.
Use the appropriate helper function for this.

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < b93fa8dc521d00d2d44bf034fb90e0d79b036617`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 0e8b8c326c2a6de4d837b1bb034ea704f4690d77`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1cd60e0d0fb8f0e62ec4499138afce6342dc9d4c`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 9c05d44ec24126fc283835b68f82dba3ae985209`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < ed3044b9c810c5c24eb2830053fbfe5fd134c5d4`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 8019b3699289fce3f10b63f98601db97b8d105b0`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 0b32ff285ff6f6f1ac1d9495787ccce8837d6405`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < dd91c79e4f58fbe2898dac84858033700e0e99fb`
- `Linux 2.6.12`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.