[CVE-2025-68294][MODERATE 7.0] io_uring/net: ensure vectored buffer node import is tied to notification

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

CVE: CVE-2025-68294
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: io_uring/net: ensure vectored buffer node import is tied to notification
Commit: 14459281e027f23b70885c1cc1032a71c0efd8d7
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=14459281e027f23b70885c1cc1032a71c0efd8d7
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-68294
Analysis date: Wed, 09 Sep 2026 02:47:02 -0400
ActionableScore: 6
ActionableScore lower bound: 5
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2025-68294 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-68294

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2025-68294	MODERATE	https://www.kernelcve.org/list/?q=CVE-2025-68294 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-416;*CWE-664;CWE-825;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.8';DESCR 'A lifetime mismatch in the io_uring/net zerocopy send path can occur because vectored registered buffer import was attached to the main req instead of the notification io_kiocb sr notif. The main request and the notification request can have different lifetimes, so the registered buffer node may be released or tracked against the wrong owner while zerocopy completion still depends on it. This is a local io_uring issue and is not directly network reachable from a remote attacker. For the CVSS the PR:L is used because a local user or process must be able to use io_uring and submit the affected zerocopy send operation with registered vectored buffers. Impact is at least local denial of service via kernel crash and in the paranoid case may include confidentiality and integrity impact because the patch context supports a UAF style lifetime bug rather than a pure warning or resource leak.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 6) 	MAYBE	SIMPLEFIX IO_URING KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP	-	-	checked

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

ActionableScore=6
ActionableScoreLower=5
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

1. ActionableScore

* Raw conservative score: 5
* Conservative score: 5. No floor or cap changed the score.
* Raw paranoid score: 6
* Paranoid score: 6. No floor or cap changed the score.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

Conservative positive signals:

* +2 Real UAF / active lifetime violation. The patch directly says the vectored registered buffer import was attached to req instead of sr->notif, while the two io_kiocb objects may have different lifetimes. This establishes a concrete ownership/lifetime mismatch where resources needed by zerocopy notification may be tracked against the wrong request.
* +1 Local unprivileged trigger. io_uring sendmsg zerocopy with registered buffers is a local userspace API and no host-admin-only prerequisite is established by the supplied patch.
* +1 Local unprivileged high-control kernel data-plane API. The attacker controls io_uring requests, registered buffer selection, vectored buffer layout, and request lifetime properties relevant to the bug.
* +1 Reliable kernel crash / strong DoS. A stale lifetime association in the zerocopy notification path can plausibly lead to kernel invalid access or crash when completion still depends on the imported buffer node.

Paranoid additional signal:

* +1 Attacker-influenced active-object state / repeatable lifetime manipulation. The same local process can repeatedly submit affected zerocopy send operations with registered vectored buffers and influence request versus notification lifetime, leaving meaningful unresolved exploitation analysis.

Negative signals:

* 0 No host-admin penalty. Host-admin-equivalent privilege is not established.
* 0 No race/timing penalty. The issue is primarily a lifetime ownership mismatch, not an externally narrow one-shot race.
* 0 No rare subsystem penalty. io_uring and TCP send paths are common enough that rarity is not a supported reducing signal.

Material non-awarded signals:

* Controlled reclaim is not demonstrated.
* Arbitrary or directed kernel write is not demonstrated.
* Remote network reachability is not established. The vulnerable operation is local submission of io_uring network I/O, not remote packet handling.
* Concrete repeated release/refcount mutation is not established from the supplied diff. The issue is wrong owner/lifetime tracking, not a visible second put on the exact same reference.
* Structured stale-object leverage is not awarded separately because the visible patch does not show a distinct post-free field-consumption mechanism beyond the ownership mismatch.
* Weak LPE is not separately awarded because that would double-count the unresolved UAF-style lifetime risk.
* Extra Availability is not awarded because the same expected crash is already counted once.
* Confidentiality and integrity bonuses are not awarded in ActionableScore because no disclosure, arbitrary write, controlled reclaim, or demonstrated LPE is established.

Repeated-release/refcount checklist:

* First release can end lifetime: unresolved from supplied diff.
* Exact same reference survives to a second lifetime mutation: not established.
* Second operation is a real lifetime/refcount mutation: not visible.
* +1 Concrete repeated release/refcount awarded: no.
* Paranoid repeated-refcount leverage +1 awarded: no.
* FLOOR 5 applied: not needed. Raw conservative score already reaches 5 through active lifetime violation plus local high-control reachability.

3. Reachability analysis

The evaluated attacker is a local userspace process able to use io_uring and submit sendmsg zerocopy operations with registered vectored buffers. This is below host-admin in normal kernel interface terms, so HostAdminRequired=NO.

The issue is not namespace-scoped privilege based. No CAP_NET_ADMIN or namespace-local capability chain is required by the supplied evidence, so NamespaceScopedPrivilege=NO rather than YES or UNKNOWN.

No remote network attacker path is established. Although the code is under io_uring/net and sends network data, the vulnerable action is local control-plane submission of an io_uring request, not packet processing of attacker-supplied network traffic.

No prior privileged host setup is established beyond normal availability of io_uring and the relevant kernel feature. There is no special hardware prerequisite in the supplied patch. The bug is not scored as a hard race because the commit describes mismatched request ownership and lifetime, not a narrow timing-only window.

4. Primitive and severity interpretation

The exact primitive is an active kernel lifetime / ownership mismatch in the zerocopy send path. The vectored registered buffer node was imported against the main io_kiocb req even though its lifetime should be tied to the notification io_kiocb sr->notif. Since req and sr->notif can have different lifetimes, the imported buffer resource can be released or tracked under the wrong owner while zerocopy completion still relies on it.

This is an active structured lifetime bug rather than fixed stale storage. The objects involved are io_kiocb request structures and registered buffer tracking state used by asynchronous network I/O completion.

The demonstrated consequence is at least local DoS through kernel crash or invalid access. The speculative consequence is stronger exploitation through UAF-style lifetime confusion, but controlled reclaim, arbitrary read/write, callback control, or credential impact is not established from the supplied patch.

PrimitiveClass=CLASS_B because a real potentially exploitable kernel lifetime primitive is established, but no Class A primitive such as controlled reclaim, arbitrary write, callback control, demonstrated LPE, or authorization bypass is shown.

ImportantCandidate=YES because the bug is a local unprivileged high-control io_uring lifetime/ownership issue with unresolved exploitation leverage beyond ordinary crash-only behavior. AutoDowngradeAllowed=NO because automatically closing this as ordinary Moderate would discard a concrete active lifetime primitive reported in a high-risk interface.

Likely operational severity is Actionable Moderate at minimum, with Strong Important review justified if further analysis shows controlled reclaim, stable stale-object reuse, or a privilege escalation path.

5. One-sentence report phrase

A lifetime mismatch in io_uring zerocopy send handling ties vectored registered buffer import to the main request instead of the notification request, allowing a local user with io_uring access to create a UAF style condition that can cause kernel DoS and requires manual review for possible stronger exploitation.

6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a local high-control io_uring lifetime/ownership bug with RealUAF=YES and unresolved exploitation leverage. It should not be automatically downgraded without reviewing the registered buffer node lifetime, notification completion path, and possible stale-object reuse.

7. Call-site confidence

Call-site confidence: medium

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

Patch: io_uring/net: ensure vectored buffer node import is tied to notification
Commit: 14459281e027f23b70885c1cc1032a71c0efd8d7
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=14459281e027f23b70885c1cc1032a71c0efd8d7

Commit description:

When support for vectored registered buffers was added, the import
itself is using 'req' rather than the notification io_kiocb, sr->notif.
For non-vectored imports, sr->notif is correctly used. This is important
as the lifetime of the two may be different. Use the correct io_kiocb
for the vectored buffer import.

Cc: stable@vger.kernel.org
Fixes: 23371ea ("io_uring/net: implement vectored reg bufs for zctx")
Reported-by: Google Big Sleep <big-sleep-vuln-reports+bigsleep-463332873@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  io_uring/net.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=14459281e027f23b70885c1cc1032a71c0efd8d7

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

The original Linux kernel CVE announcement for CVE-2025-68294 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-68294

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:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 5
  Paranoid ActionableScore: 6

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).