---
id: CVE-2026-63995
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ethtool: cmis: validate start_cmd_payload_size from module

  The CMIS firmware update code reads start_cmd_payload_size from
  the module's FW Management Features CDB repl…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ethtool: cmis: validate start_cmd_payload_size from module

  The CMIS firmware update code reads start_cmd_payload_size from
  the module's FW Management Features CDB repl…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-787
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.11, < 6.12.93'
  - 'linux_kernel >= 6.13, < 6.18.35'
  - 'linux_kernel >= 6.19, < 7.0.12'
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.12
published: '2026-07-19'
updated: '2026-10-07'
sourceUpdated: '2026-10-07T20:26:18.313'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63995'
references:
  - url: 'https://git.kernel.org/stable/c/0696709e951be54c699664adf546d16e28974d53'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/12c2496a71f82f63617971ca9b730dffa05cf58b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/63112b4515469d00008452d9cfe3fb3bf1aa2df3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a46340da00385be7fb16c62425ebc20006f2d5d8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00129
epssPercentile: 0.02145
ingestedAt: '2026-10-07T20:46:46.958Z'
---

## Overview

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

ethtool: cmis: validate start_cmd_payload_size from module

The CMIS firmware update code reads start_cmd_payload_size from
the module's FW Management Features CDB reply and uses it directly
as the byte count for memcpy. The destination buffer is 112 bytes
(ETHTOOL_CMIS_CDB_LPL_MAX_PL_LENGTH - 8). So a malicious
module (or corrupted response) can cause a OOB write later on in
cmis_fw_update_start_download().

Let's error out. If modules that expect longer LPL writes actually
exist we should revisit.

struct cmis_cdb_start_fw_download_pl's definition has to move,
no change there.

## Affected

- `linux_kernel >= 6.11, < 6.12.93`
- `linux_kernel >= 6.13, < 6.18.35`
- `linux_kernel >= 6.19, < 7.0.12`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.12`