[CVE-2026-89975][LOW] nvme-fabrics: fix DHCHAP secret leak on parse failure

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-89975
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: nvme-fabrics: fix DHCHAP secret leak on parse failure
Commit: 702c1ae0d31b44828ec3c87079def490c1ee1fb3
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=702c1ae0d31b44828ec3c87079def490c1ee1fb3
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89975
Analysis date: Wed, 16 Sep 2026 15:24:59 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-89975 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89975

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: LOW
Manual review required: NO

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

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

CVE-2026-89975	LOW	https://www.kernelcve.org/list/?q=CVE-2026-89975 CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'Resource leak only. No memory corruption primitive is visible from the diff. Base score assumes normal root only access to /dev/nvme-fabrics. Paranoid score assumes delegated local storage management can repeatedly trigger the parse failure and eventually exhaust memory.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	YES	NVME LEAK ERRORPATH UAF IMPROVEONLY LINUS  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	YES	NO	checked

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

ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1. No floor or cap applied.
* Raw paranoid score: 2
* Paranoid score: 2. No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 conservative: concrete persistent kernel resource leak. `match_strdup()` allocates a temporary DHCHAP secret string, validation fails before ownership is transferred into `opts`, and normal cleanup cannot free the temporary allocation.
* +1 paranoid: deterministic repeated malformed writes can accumulate leaked allocations and may eventually cause resource pressure. This is resource exhaustion only, not memory corruption.
* 0: no UAF. The patch fixes a lost allocation, not stale post-lifetime object use.
* 0: no repeated release or refcount mutation. There is no first release followed by a second lifetime-mutating operation on the same dangling reference.
* 0: no controlled reclaim, arbitrary write, OOB access, type confusion, callback control, or kernel memory corruption is established.
* 0: no confidentiality or integrity signal. `kfree_sensitive()` is appropriate cleanup for secret-like material, but the bug is a leak of kernel memory allocation ownership, not a demonstrated disclosure path.
* 0: no reliable immediate kernel crash is established. DoS is only through accumulated memory/resource exhaustion.
* 0: no remote reachability. The trigger is local writes to `/dev/nvme-fabrics`, not traffic from an NVMe-oF target.
* No negative privilege penalty applied. Access to `/dev/nvme-fabrics` is commonly administrative, but the supplied evidence does not fully prove the exact host-admin boundary for all deployments.

3. Reachability analysis

The vulnerable path is reached locally through the NVMe fabrics control interface by writing malformed options such as `dhchap_secret=BAD` or `dhchap_ctrl_secret=BAD` to `/dev/nvme-fabrics`.

`CONFIG_NVME_HOST_AUTH` must be enabled. No NVMe-oF target, working transport connection, or remote endpoint is required because the leak happens during option parsing before required-option checks and transport lookup.

The complete trigger is not network-scoped and is not namespace-scoped based on the supplied evidence. The likely practical actor is a local storage-management process or administrator-equivalent user, but host-admin-equivalent privilege is not conclusively established from the supplied patch text alone, so `HostAdminRequired=UNKNOWN`.

No race is involved. The leak path is deterministic once the malformed option is parsed.

4. Primitive and severity interpretation

The exact primitive is a local persistent allocation leak on parse failure. `p` is allocated by `match_strdup()`, rejected by DHHC-1 format validation, and then lost because it has not yet been assigned to `opts->dhchap_secret` or `opts->dhchap_ctrl_secret`.

This is not active structured object corruption and not fixed stale storage UAF. It is a resource-management bug with possible local resource-exhaustion consequences after repeated triggering.

Primitive class is `CLASS_C` because the demonstrated behavior is DoS/resource exhaustion without an independently useful corruption, ownership, authorization, or lifetime-refcount mutation primitive.

ImportantCandidate is `NO` because there is no memory corruption, no UAF, no security-boundary bypass, no COW or ownership violation, and no demonstrated path to LPE or protected-resource access.

AutoDowngradeAllowed is `YES` because the issue is a resource leak only and does not leave unresolved Important-grade exploitation leverage.

Likely operational severity is ordinary Moderate or Low-like depending on local access policy to `/dev/nvme-fabrics`.

5. One-sentence report phrase

A local malformed DHCHAP option written to /dev/nvme-fabrics can leak one temporary kernel allocation per rejected parse when CONFIG_NVME_HOST_AUTH is enabled, potentially causing resource exhaustion after repeated attempts.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: this is a deterministic resource leak without UAF, memory corruption, authorization bypass, remote reachability, or privilege-escalation evidence.

7. Call-site confidence

Call-site confidence: high

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

Patch: nvme-fabrics: fix DHCHAP secret leak on parse failure
Commit: 702c1ae0d31b44828ec3c87079def490c1ee1fb3
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=702c1ae0d31b44828ec3c87079def490c1ee1fb3

Commit description:

nvmf_parse_options() duplicates dhchap_secret and dhchap_ctrl_secret
with match_strdup() before validating the DHHC-1: representation.

If validation fails, the parser returns -EINVAL before the temporary
string in p is assigned to opts->dhchap_secret or
opts->dhchap_ctrl_secret. nvmf_create_ctrl() subsequently frees opts,
but nvmf_free_options() cannot release the unassigned temporary string.
Each rejected option therefore leaks one allocation.

This is easy to miss because valid secrets transfer ownership to opts
and are freed normally, while the malformed-secret path still returns
the expected -EINVAL to userspace.

With CONFIG_NVME_HOST_AUTH enabled, the leak is reachable before the
required-option checks and transport lookup. No NVMe-oF target or
working transport connection is required; for example, repeatedly
writing

	dhchap_secret=BAD

or

	dhchap_ctrl_secret=BAD

to /dev/nvme-fabrics deterministically takes the leaking parse path.

Free the temporary string before leaving both validation error paths.
Use kfree_sensitive() because the copied option may contain secret
material even when its representation is rejected, matching the
sensitive cleanup used for stored DHCHAP secrets.

Fixes: f50fff7 ("nvme: implement In-Band authentication")
Cc: stable@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Xu Rao <raoxu@uniontech.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/nvme/host/fabrics.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=702c1ae0d31b44828ec3c87079def490c1ee1fb3

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

The original Linux kernel CVE announcement for CVE-2026-89975 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89975

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:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

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: 1
  Paranoid ActionableScore: 2

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).