[CVE-2025-10263][MODERATE 7.0] arm64: errata: Mitigate TLBI errata on various Arm CPUs

[CVE-2025-10263][MODERATE 7.0] arm64: errata: Mitigate TLBI errata on various Arm CPUs

[AL-KERNEL]

CVE: CVE-2025-10263
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: arm64: errata: Mitigate TLBI errata on various Arm CPUs
Commit: 925058203229403008d77a52b1e63e2ae5f4a3cf
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=925058203229403008d77a52b1e63e2ae5f4a3cf
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-10263
Analysis date: Wed, 01 Jul 2026 10:20:23 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
CVE-2025-10263 mitigates an Arm TLBI completion erratum where affected CPUs may complete a broadcast TLBI DSB sequence before related writes are globally observed, creating a local hardware-dependent risk of stale memory effects, data corruption, or kernel crash.

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

The original Linux kernel CVE announcement for CVE-2025-10263 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-10263

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-2025-10263	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-362;CWE-693;*CWE-664;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'On affected Arm CPUs, a broadcast TLBI DSB sequence may complete before writes translated by an invalidated TLB entry are globally observed. This can break kernel assumptions around page table teardown, mapping changes, and page reuse, potentially causing stale memory effects, data corruption, or a kernel crash. For the CVSS the PR:L is used because a local user or process is generally required to create the relevant memory management activity and timing conditions. The issue is not directly network reachable. Impact is at least local denial of service and data integrity risk, and in the paranoid case may include broader confidentiality and integrity impact because the bug class can affect memory isolation semantics. For the paranoid score, choose the highest still defensible interpretation supported by the hardware erratum and patch context, with preference for manual-review sensitivity over autoclosed false negatives.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 5) 	YES	HARDWARE  KPANIC INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS	NO	NO	checked

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

ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: **4**
* Paranoid score: **5**
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Triggered signals:

* **Local unprivileged trigger: +1**
  A local process can plausibly create memory-management churn through mmap, munmap, fork, exit, mprotect, page-table teardown, and page reuse paths, even though it does not directly execute TLBI.

* **Memory corruption, weak/indirect corruption candidate: +1**
  The patch does not show a classic UAF, OOB write, double-free, or arbitrary write primitive, but the erratum can break ordering assumptions around invalidated TLB entries and globally visible writes. This is a weak but real memory-state corruption concern.

* **Availability impact realistic: +1**
  Broken TLBI completion semantics can plausibly cause kernel crashes, data inconsistency, or hard-to-debug system instability on affected CPUs.

* **Integrity impact plausible: +1**
  Delayed global visibility of writes around mapping teardown or page reuse can plausibly corrupt memory state or violate expected ordering between address spaces.

* **Broad/default/common subsystem exposure: +1**
  This affects core arm64 MMU/TLB maintenance behavior on many Arm Cortex, Neoverse, and C1 CPU families, not a narrow driver-only path.

Subtracting signals:

* **Hard timing / architecture-dependent condition: -1**
  Reliable triggering requires specific affected CPU models and timing-sensitive memory-management behavior.

Paranoid-only additional concern:

* **Weak LPE / confidentiality concern: +1**
  In the paranoid interpretation, stale memory effects around page-table invalidation and page reuse could affect isolation semantics. This is not a demonstrated exploit primitive, but it is enough to avoid auto-closure.

## 3. Reachability analysis

The issue is **not network reachable** by itself. A local process is the realistic trigger source because it can cause memory mapping changes and page-table churn that force kernel TLBI sequences. No special userspace privilege is obviously required to create such memory-management activity, but reliable exploitation depends on affected Arm hardware and difficult timing.

Namespaces and containers may matter because containerized workloads can still generate mmap, fork, exit, and page-table activity on the host kernel. The path is architecture and hardware dependent, but the affected CPU list is broad enough that this should not be treated as a rare niche-only driver bug.

Call-site confidence: **medium**. The patch does not include direct call-site failure traces, but TLBI/DSB ordering is core MMU machinery and the erratum description directly explains the violated invariant.

## 4. Severity interpretation

This behaves like an **Actionable Moderate at minimum**, with **Strong Important candidate** justification for manual review on affected Arm systems. The conservative view is that this is a difficult, hardware-dependent local stability and integrity issue. The paranoid view is higher because stale write visibility around invalidated TLB entries can undermine memory isolation assumptions, even without a demonstrated arbitrary write or UAF reclaim primitive.

Theoretical memory-corruption potential exists through stale memory effects and broken ordering. Realistic exploitation evidence is weaker: the patch does not demonstrate controlled reclaim, arbitrary write, information disclosure, or a concrete LPE chain.

## 5. One-sentence report phrase

CVE-2025-10263 mitigates an Arm TLBI completion erratum where affected CPUs may complete a broadcast TLBI DSB sequence before related writes are globally observed, creating a local hardware-dependent risk of stale memory effects, data corruption, or kernel crash.

## 6. Manual review recommendation

**MANUAL CHECK REQUIRED**

Reason: this is a core arm64 MMU/TLB ordering erratum affecting many CPU families. Even though exploitation is timing-sensitive and hardware-dependent, the affected primitive touches memory isolation and page-table lifecycle assumptions, so auto-closing as ordinary Moderate would be risky.

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

Patch: arm64: errata: Mitigate TLBI errata on various Arm CPUs
Commit: 925058203229403008d77a52b1e63e2ae5f4a3cf
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=925058203229403008d77a52b1e63e2ae5f4a3cf

Commit description:

A number of CPUs developed by Arm suffer from errata whereby a broadcast
TLBI;DSB sequence may complete before the global observation of writes
which are translated by an affected TLB entry.

These errata ONLY affect the completion of memory accesses which have
been translated by an invalidated TLB entry, and these errata DO NOT
affect the actual invalidation of TLB entries. TLB entries are removed
correctly.

This issue has been assigned CVE ID CVE-2025-10263 .

To mitigate this issue, Arm recommends that software follows any
affected TLBI;DSB sequence with an additional TLBI;DSB, which will
ensure that all memory write effects affected by the first TLBI have
been globally observed. The additional TLBI can use any operation that
is broadcast to affected CPUs, and the additional DSB can use any option
that is sufficient to complete the additional TLBI.

The ARM64_WORKAROUND_REPEAT_TLBI workaround is sufficient to mitigate
the issue. Enable this workaround for affected CPUs, and update the
silicon errata documentation accordingly.

Note that due to the manner in which Arm develops IP and tracks errata,
some CPUs share a common erratum number.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
[Mark: backport to v5.10.y]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  arch/arm64/kernel/cpu_errata.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=925058203229403008d77a52b1e63e2ae5f4a3cf

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

The original Linux kernel CVE announcement for CVE-2025-10263 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-10263

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:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7

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).