---
id: CVE-2026-74556
title: 'scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer

  iscsi_tcp_hdr_dissect() receives the data segment of several PDU types
  into the fixed-siz…
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'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff <
    a51812842084fd390590ab8dc0431f10c73ddc56
  - >-
    Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff <
    a8f94cc9f0e5759252551be3a172960c57f21f54
  - >-
    Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff <
    f1a3a51fc5dba0e99532379665069f1700da6b44
  - >-
    Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff <
    c97b5265cc47775f77fd2a23d6bde0426997b233
  - >-
    Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff <
    084af0253673425ce2ae62e3c7f74f0dd023711b
  - >-
    Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff <
    72815741715bd41556dac5eeb068bf0f8af06ee7
  - >-
    Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff <
    b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676
  - >-
    Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff <
    c1dea15f819cded9b3faf58f8bec72323568b6e6
  - Linux 2.6.29
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T19:00:06.190671Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:05:55.568Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74556'
references:
  - url: 'https://git.kernel.org/stable/c/a51812842084fd390590ab8dc0431f10c73ddc56'
  - url: 'https://git.kernel.org/stable/c/a8f94cc9f0e5759252551be3a172960c57f21f54'
  - url: 'https://git.kernel.org/stable/c/f1a3a51fc5dba0e99532379665069f1700da6b44'
  - url: 'https://git.kernel.org/stable/c/c97b5265cc47775f77fd2a23d6bde0426997b233'
  - url: 'https://git.kernel.org/stable/c/084af0253673425ce2ae62e3c7f74f0dd023711b'
  - url: 'https://git.kernel.org/stable/c/72815741715bd41556dac5eeb068bf0f8af06ee7'
  - url: 'https://git.kernel.org/stable/c/b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676'
  - url: 'https://git.kernel.org/stable/c/c1dea15f819cded9b3faf58f8bec72323568b6e6'
tags:
  - cve.org
epss: 0.00399
epssPercentile: 0.32547
ingestedAt: '2026-10-16T19:46:24.345Z'
---

## Overview

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

scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer

iscsi_tcp_hdr_dissect() receives the data segment of several PDU types
into the fixed-size conn->data buffer, which is allocated for
ISCSI_DEF_MAX_RECV_SEG_LEN (8192) bytes.  For the LOGIN_RSP, TEXT_RSP,
REJECT and ASYNC_EVENT opcodes the dissect path already rejects a PDU
whose DataSegmentLength exceeds that buffer.

The SCSI Command Response (ISCSI_OP_SCSI_CMD_RSP) path also copies its
data segment (sense/response data) into conn->data via
iscsi_tcp_data_recv_prep(), but it does so without the same check.  The
only upstream bound on in.datalen is conn->max_recv_dlength, the
initiator's advertised MaxRecvDataSegmentLength, which is commonly
negotiated well above 8192 (open-iscsi defaults to 262144).  A target
that returns a SCSI Response with a DataSegmentLength between 8193 and
max_recv_dlength therefore overflows the 8192-byte conn->data buffer.

Once the same bound applies, ISCSI_OP_SCSI_CMD_RSP is handled exactly
like those responses: bound the data segment, receive it into conn->data
when present, and otherwise complete the PDU with no data.  Fold the
opcode into that case group rather than duplicating the check.

## Affected

- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < a51812842084fd390590ab8dc0431f10c73ddc56`
- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < a8f94cc9f0e5759252551be3a172960c57f21f54`
- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < f1a3a51fc5dba0e99532379665069f1700da6b44`
- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < c97b5265cc47775f77fd2a23d6bde0426997b233`
- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < 084af0253673425ce2ae62e3c7f74f0dd023711b`
- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < 72815741715bd41556dac5eeb068bf0f8af06ee7`
- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676`
- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < c1dea15f819cded9b3faf58f8bec72323568b6e6`
- `Linux 2.6.29`

## Remediation

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