---
id: CVE-2026-89969
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU

  nvmet_tcp_try_recv_pdu() reads a PDU header into the fixed 128-byte
  queue->pdu union, then computes …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU

  nvmet_tcp_try_recv_pdu() reads a PDU header into the fixed 128-byte
  queue->pdu union, then computes …
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 <
    a3f0bcfbaf3312a5754d1ce020a07d394669eb25
  - >-
    Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 <
    4f84d42c53c49557fb1ef285c683b0a81b576c74
  - >-
    Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 <
    58dc6035b79c4c73c0cbf9ec9f68a7f117b2b3e6
  - >-
    Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 <
    cf5f39d2b58f97e0cd1829c4a6aeef17f1607cca
  - >-
    Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 <
    3a385e0c39efbe34db8edd95900c123113ae3450
  - >-
    Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 <
    dbc4acbdb3ca8c81441368ad7409b8f77d4de8f6
  - >-
    Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 <
    d95d342bc0ea82dc79e6362b2f1f997431750e4c
  - >-
    Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 <
    14cc5a7e77731497d5bea70f3bb05df7eda982e4
  - Linux 5.0
published: '2026-09-16'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T15:18:21.240'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89969'
references:
  - url: 'https://git.kernel.org/stable/c/14cc5a7e77731497d5bea70f3bb05df7eda982e4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3a385e0c39efbe34db8edd95900c123113ae3450'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4f84d42c53c49557fb1ef285c683b0a81b576c74'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/58dc6035b79c4c73c0cbf9ec9f68a7f117b2b3e6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a3f0bcfbaf3312a5754d1ce020a07d394669eb25'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/cf5f39d2b58f97e0cd1829c4a6aeef17f1607cca'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d95d342bc0ea82dc79e6362b2f1f997431750e4c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dbc4acbdb3ca8c81441368ad7409b8f77d4de8f6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-16T10:53:53.956Z'
epss: 0.00695
epssPercentile: 0.51542
---

## Overview

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

nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU

nvmet_tcp_try_recv_pdu() reads a PDU header into the fixed 128-byte
queue->pdu union, then computes the remaining payload length as

	queue->left = hdr->hlen - queue->offset + hdgst;

and reads that many more bytes into &queue->pdu + queue->offset, without
ever bounding the result against sizeof(queue->pdu).

A struct nvme_tcp_icreq_pdu is itself 128 bytes, exactly the size of the
union. Once a header digest has been negotiated (hdgst = 4), a second
ICReq passes the hlen == nvmet_tcp_pdu_size() check but yields
queue->left = 128 - 8 + 4 = 124, so bytes 8..132 are written into the
128-byte buffer -- 4 bytes past its end, over queue->hdr_digest and
queue->data_digest. Those bytes are attacker-controlled (an ICReq
carries no digest), and the duplicate ICReq is only rejected later,
after the overflow. A remote unauthenticated host can thus corrupt
kernel memory adjacent to the receive buffer.

Reject any PDU whose declared length would read past the end of
queue->pdu before the second recv.

## Remediation

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