[CVE-2026-74557][MODERATE 7.0] scsi: libiscsi: Fix stale-data leak into the SCSI sense buffer [ Upstream

[CVE-2026-74557][MODERATE 7.0] scsi: libiscsi: Fix stale-data leak into the SCSI sense buffer [ Upstream

[AL-KERNEL]

CVE: CVE-2026-74557
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: scsi: libiscsi: Fix stale-data leak into the SCSI sense buffer [ Upstream
Commit: 7567f06abdefb1caf2d836107c4d08c5185c650e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7567f06abdefb1caf2d836107c4d08c5185c650e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74557
Analysis date: Sat, 15 Aug 2026 11:57:05 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
No one-sentence report phrase was found.

======================================================================
ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-74557 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74557

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: MODERATE 7.0
Manual review required: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-74557	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N';CWE-126;CWE-125;*CWE-200;Other CVSS 'AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.3';DESCR 'iscsi_scsi_cmd_rsp() can copy stale data into the SCSI sense buffer because the bounds check accounts for senselen but not for the 2 byte sense length prefix before the sense bytes. A malicious or compromised iSCSI target can return a crafted SCSI Response where datalen equals senselen, causing memcpy from data plus 2 to read up to two bytes past the received segment and expose stale conn data to userspace through the command sense buffer. For the CVSS the PR:N is used for the paranoid score because the attacker does not need local privileges on the initiator and only needs the ability to send target responses over an established iSCSI storage connection. The issue is network reachable in environments where the initiator connects to an attacker controlled or compromised target. Impact is an information leak only with C:L and I:N/A:N. iSCSI is typically deployed inside isolated storage or data center networks and is usually not exposed to the public Internet.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	OOB SIMPLEFIX LEAK HARDWARE  KPANIC INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS	NO	NO	checked

======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=5
ActionableScoreLower=4

1. ActionableScore
* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

2. Signal breakdown
* Remote reachable / network-triggerable: +2. A malicious or compromised iSCSI target can send the crafted SCSI Response over an established iSCSI connection.
* Confidentiality impact plausible: +1. The bug leaks up to two stale bytes from conn data into the SCSI sense buffer returned to userspace.
* Important filesystem/storage path: +1. The issue is in libiscsi SCSI response handling, a storage protocol path.
* Practical exploit chain demonstrated or strongly implied: +1 in paranoid score only. The commit describes the exact malformed response condition and the user-visible disclosure path.
* No generic memory corruption bonus. This is a bounded read past received data, not UAF, overwrite, double-free, type confusion, or refcount misuse.
* No integrity or availability bonus. The patch supports stale-data disclosure only.

3. Reachability analysis
The attacker needs to control or compromise the iSCSI target, or otherwise influence target responses on an established iSCSI session. No local privileges are required on the initiator for the attacker side, so PR:N is reasonable for CVSS-style paranoid scoring. The path is not Internet-default exposure, since iSCSI is usually deployed on isolated storage or data-center networks, but it is still realistically network-triggerable in storage environments.

4. Severity interpretation
This behaves like an actionable Moderate information leak, not an Important memory-corruption issue. The realistic impact is small confidentiality disclosure, limited to stale bytes from conn data reaching userspace via sense data. Theoretical escalation is not supported by the patch because there is no write primitive, lifetime corruption, or attacker-controlled object reuse.

5. One-sentence report phrase
A malicious or compromised iSCSI target can craft a SCSI Response with an insufficient data segment length, causing libiscsi to copy up to two stale bytes into the userspace-visible SCSI sense buffer.

6. Manual review recommendation
MANUAL CHECK REQUIRED. YES REQUIRES MANUAL CHECK.
Reason: network-triggerable information leaks in storage protocol paths should not be auto-closed, even though this specific leak is small and does not show memory corruption.

======================================================================
UPSTREAM PATCH SUMMARY
======================================================================

Patch: scsi: libiscsi: Fix stale-data leak into the SCSI sense buffer [ Upstream
Commit: 7567f06abdefb1caf2d836107c4d08c5185c650e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7567f06abdefb1caf2d836107c4d08c5185c650e

Changed files:
  drivers/scsi/libiscsi.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7567f06abdefb1caf2d836107c4d08c5185c650e

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-74557 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74557

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
  The Best / paranoid CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
  The Best / paranoid CVSS score: 5.3

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: 4
  Paranoid ActionableScore: 5

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): MODERATE 7.0

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).