[CVE-2026-68092][LOW] time/jiffies: Register jiffies clocksource before usage [ Upstream

[CVE-2026-68092][LOW] time/jiffies: Register jiffies clocksource before usage [ Upstream

[AL-KERNEL]

CVE: CVE-2026-68092
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: time/jiffies: Register jiffies clocksource before usage [ Upstream
Commit: fe9bdea65ba231fcfb155031628bb1e8491b5fe0
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fe9bdea65ba231fcfb155031628bb1e8491b5fe0
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68092
Analysis date: Mon, 10 Aug 2026 12:28:05 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
The jiffies clocksource may be used before registration during early boot, causing time reads to be clamped and producing a long boot delay or boot-time denial of service on affected Xen HVM guests.

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

The original Linux kernel CVE announcement for CVE-2026-68092 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68092

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-2026-68092	LOW	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';CWE-665;*CWE-664;CWE-754;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.1';DESCR 'The jiffies clocksource can be used during early boot before it is registered, leaving max_delta_raw as 0 and causing time reads to be clamped so time does not progress. On affected Xen HVM guests this can lead to a long boot delay or boot time denial of service, but the patch does not indicate a memory corruption primitive, UAF, OOB access, or privilege escalation path. For the CVSS the PR:H is used because reliable triggering depends on controlling the boot environment, kernel version, or virtual platform configuration rather than on an unprivileged local interface. The issue is not network reachable and has availability impact only.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)  SKIP CVE-2026-68092 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: 76031d9536a076bf023bedbdb1b4317fc801dd67 YES  NO NO unknown 	MAYBE	INIT SIMPLEFIX LINUS  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=1
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Conservative signals:

* Requires admin/root/boot-environment control: -2. Reliable triggering depends on kernel version, boot path, and Xen HVM or similar virtual platform behavior, not on an unprivileged runtime interface.
* Rare or configuration-dependent trigger: -1. The reported symptom is tied to early boot clocksource ordering on Xen HVM after a specific timekeeping change.
* No memory corruption signal: 0. The patch shows initialization ordering only. No UAF, OOB, double free, refcount issue, arbitrary write, or stale pointer primitive is indicated.
* No confidentiality or integrity impact: 0. The failure mode is time not progressing during early boot.
* Availability impact exists but is not attacker-reachable in normal operation: +1 at most. The realistic effect is long boot delay or boot-time DoS.

Paranoid adjustment:

* Boot-time availability DoS: +1. If the system reliably stalls during boot on affected Xen HVM configurations, this can be operationally significant, but still not security-boundary crossing.

## 3. Reachability analysis

The issue is not network reachable and is not triggerable by a normal local unprivileged user after the system has booted. Practical triggering requires controlling or selecting an affected kernel and boot environment, or operating an affected Xen HVM configuration. Namespaces and containers do not meaningfully reduce the privilege requirement because the bug occurs before normal userspace/container attack surfaces are available.

Call-site confidence: high. The patch directly changes `clocksource_default_clock()` and the commit explains the early use before registration.

## 4. Severity interpretation

This behaves like a low-risk initialization/order bug with availability impact only. It does not behave like an actionable Moderate or Important kernel vulnerability because there is no memory corruption primitive, no privilege escalation path, no sensitive data exposure, and no runtime unprivileged trigger. Theoretical impact is boot delay or boot-time DoS, while realistic exploitation evidence is limited to affected virtual boot configurations.

## 5. One-sentence report phrase

The jiffies clocksource may be used before registration during early boot, causing time reads to be clamped and producing a long boot delay or boot-time denial of service on affected Xen HVM guests.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for security triage because it is a boot-time initialization bug with no memory corruption, no network reachability, no privilege escalation evidence, and only availability impact in a specific virtualized boot scenario.

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

Patch: time/jiffies: Register jiffies clocksource before usage [ Upstream
Commit: fe9bdea65ba231fcfb155031628bb1e8491b5fe0
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fe9bdea65ba231fcfb155031628bb1e8491b5fe0

Changed files:
  kernel/time/jiffies.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=fe9bdea65ba231fcfb155031628bb1e8491b5fe0

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

The original Linux kernel CVE announcement for CVE-2026-68092 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68092

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:H/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.1

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: 0
  Paranoid ActionableScore: 1

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).