Bug 2517010 (CVE-2026-74556) - CVE-2026-74556 kernel: scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer
Summary: CVE-2026-74556 kernel: scsi: libiscsi_tcp: Bound SCSI Response data segment t...
Keywords:
Status: NEW
Alias: CVE-2026-74556
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-15 12:44 UTC by OSIDB Bzimport
Modified: 2026-10-07 03:39 UTC (History)
17 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:67468 0 None None None 2026-09-15 00:47:13 UTC
Red Hat Product Errata RHSA-2026:67469 0 None None None 2026-09-15 00:24:35 UTC
Red Hat Product Errata RHSA-2026:67470 0 None None None 2026-09-15 06:28:24 UTC
Red Hat Product Errata RHSA-2026:67471 0 None None None 2026-09-15 06:14:38 UTC
Red Hat Product Errata RHSA-2026:77216 0 None None None 2026-10-07 02:49:28 UTC
Red Hat Product Errata RHSA-2026:77217 0 None None None 2026-10-07 03:39:12 UTC

Description OSIDB Bzimport 2026-08-15 12:44:34 UTC
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.

Comment 3 Jon Orris 2026-09-15 00:24:33 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:67469 https://access.redhat.com/errata/RHSA-2026:67469

Comment 4 Jon Orris 2026-09-15 00:47:11 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:67468 https://access.redhat.com/errata/RHSA-2026:67468

Comment 5 Jon Orris 2026-09-15 06:14:36 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:67471 https://access.redhat.com/errata/RHSA-2026:67471

Comment 6 Jon Orris 2026-09-15 06:28:22 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:67470 https://access.redhat.com/errata/RHSA-2026:67470

Comment 9 Jon Orris 2026-10-07 02:49:26 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

Via RHSA-2026:77216 https://access.redhat.com/errata/RHSA-2026:77216

Comment 10 Jon Orris 2026-10-07 03:39:11 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

Via RHSA-2026:77217 https://access.redhat.com/errata/RHSA-2026:77217


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