---
id: CVE-2026-90067
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  libceph: validate banner payload length

  When parsing the Ceph messenger v2 protocol banner, the `payload_len` field
  is decoded from the banner prefix
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  libceph: validate banner payload length

  When parsing the Ceph messenger v2 protocol banner, the `payload_len` field
  is decoded from the banner prefix. If a client send…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= cd1a677cad994021b19665ed476aea63f5d54f31 <
    279c0852999fd2384f4a88155091a99e81f96873
  - >-
    Linux >= cd1a677cad994021b19665ed476aea63f5d54f31 <
    6cf666e47f2b51d5a887ec8a3226cde951757d27
  - >-
    Linux >= cd1a677cad994021b19665ed476aea63f5d54f31 <
    3b2e62a7655d347a845a91155610ddae11daffc6
  - >-
    Linux >= cd1a677cad994021b19665ed476aea63f5d54f31 <
    c1b937ff24b19e69aa7fb1b0f46a74d4c9668692
  - >-
    Linux >= cd1a677cad994021b19665ed476aea63f5d54f31 <
    6d1c6f228854aa89844fd0152d7ed7ac72a55e89
  - >-
    Linux >= cd1a677cad994021b19665ed476aea63f5d54f31 <
    c77633a9595658210a6e216a071e5a396a0835a7
  - >-
    Linux >= cd1a677cad994021b19665ed476aea63f5d54f31 <
    f374967fcdf04001c9b66df1c19106fa83cd91f7
  - Linux 5.11
published: '2026-09-17'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T18:17:40.537'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90067'
references:
  - url: 'https://git.kernel.org/stable/c/279c0852999fd2384f4a88155091a99e81f96873'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3b2e62a7655d347a845a91155610ddae11daffc6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6cf666e47f2b51d5a887ec8a3226cde951757d27'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6d1c6f228854aa89844fd0152d7ed7ac72a55e89'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c1b937ff24b19e69aa7fb1b0f46a74d4c9668692'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c77633a9595658210a6e216a071e5a396a0835a7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f374967fcdf04001c9b66df1c19106fa83cd91f7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.007
epssPercentile: 0.51144
ingestedAt: '2026-09-17T16:21:47.898Z'
---

## Overview

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

libceph: validate banner payload length

When parsing the Ceph messenger v2 protocol banner, the `payload_len` field
is decoded from the banner prefix. If a client sends a banner with a
`payload_len` of 0, the kernel sets up a 0-length socket read. This
violates an invariant in the state machine, triggering a warning in
`populate_in_iter()`:

------------[ cut here ]------------
!iov_iter_count(&con->v2.in_iter)
WARNING: net/ceph/messenger_v2.c:3129 at populate_in_iter
net/ceph/messenger_v2.c:3129 [inline], CPU#1: kworker/1:3/5070
WARNING: net/ceph/messenger_v2.c:3129 at ceph_con_v2_try_read+0x6634/0x6810
net/ceph/messenger_v2.c:3159, CPU#1: kworker/1:3/5070
...
Call Trace:
 <TASK>
 ceph_con_workfn+0x1f5/0x14a0 net/ceph/messenger.c:1575
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

According to the msgr2 protocol specification, the banner payload is
expected to contain at least two 64-bit integers (`server_feat` and
`server_req_feat`). Therefore, `payload_len` must be at least 16 bytes.

Fix this by adding a check in `process_banner_prefix()` to reject a
`payload_len` smaller than 16 bytes. This prevents the 0-length read and
correctly aborts the connection with a protocol error.

## Remediation

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