[CVE-2026-53114][MODERATE REGULAR] perf/amd/ibs: Avoid calling perf_allow_kernel() from the IBS NMI handler [ Upstream

[CVE-2026-53114][MODERATE REGULAR] perf/amd/ibs: Avoid calling perf_allow_kernel() from the IBS NMI handler [ Upstream

[AL-KERNEL]

CVE: CVE-2026-53114
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: perf/amd/ibs: Avoid calling perf_allow_kernel() from the IBS NMI handler [ Upstream
Commit: 2783ed2442ce69ae240b787aee6dae801cef7aec
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2783ed2442ce69ae240b787aee6dae801cef7aec
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53114
Analysis date: Fri, 26 Jun 2026 08:57:12 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline manual review recommended / Ordinary Moderate otherwise
Manual review required: YES

Summary:
AMD IBS perf handling could call perf_allow_kernel() from the IBS NMI handler while processing raw samples, allowing a local user with access to suitable perf events to trigger a fatal kernel condition and cause denial of service.

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

The original Linux kernel CVE announcement for CVE-2026-53114 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53114

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 REGULAR
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-2026-53114	MODERATE	CHECK	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-667;CWE-703;CWE-754;BEST CVSS score: '5.5';DESCR 'AMD IBS perf handling could call perf_allow_kernel from the IBS NMI handler while processing raw samples. Calling this permission helper from NMI context is unsafe and can be fatal, so a local user who can create a suitable perf IBS event may be able to trigger a kernel crash. For the CVSS the PR:L is used because reliable triggering requires local code execution with access to perf_event_open or an equivalent perf interface, but not full administrator privileges in permissive perf configurations. The issue is not network reachable and does not provide a demonstrated memory corruption or information disclosure primitive. Impact is denial of service via kernel crash.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended / Ordinary Moderate otherwise (with actual score 3) 	MAYBE	INIT SIMPLEFIX LEAK HARDWARE  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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

ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline manual review recommended / Ordinary Moderate otherwise**::

## 2. Signal breakdown

* Local unprivileged trigger: +1
  A local user may be able to create a suitable perf IBS event through perf_event_open if perf permissions allow it.

* Reliable kernel crash / strong DoS: +1
  The commit states that calling perf_allow_kernel() from NMI context is unsafe and could be fatal, which supports kernel crash / DoS impact.

* Availability impact realistic: +1 in paranoid score only
  Counted only in the paranoid score because a fatal NMI-context failure can be host-wide if the event is reachable and triggerable.

* Rare or configuration-dependent exposure: -1 in conservative score
  The issue depends on AMD IBS support, perf availability, and local perf permission policy. It is not a broad network or common syscall path issue.

No memory-corruption signal is counted. The patch shows an unsafe helper call from NMI context, not UAF, OOB write, double-free, object confusion, or a demonstrated corruption primitive.

## 3. Reachability analysis

The bug is locally reachable through AMD IBS perf events. In permissive configurations, an unprivileged local user may be able to create the relevant perf event, so PR:L is the practical paranoid interpretation. In hardened deployments, perf_event_paranoid, CAP_PERFMON, CAP_SYS_ADMIN, or distribution policy may restrict access, lowering practical exposure.

Namespaces and containers may matter if perf access is delegated or if a containerized workload can access host perf events, but this is not normally a remote or network-triggerable path. The affected path is hardware and configuration dependent because it requires AMD IBS and the relevant perf sampling mode.

## 4. Severity interpretation

This behaves like a local DoS issue, not an Important-class memory corruption issue. The theoretical impact is a kernel crash caused by unsafe NMI-context behavior. There is no evidence in the patch of a confidentiality leak, integrity impact, UAF reclaim primitive, arbitrary write, or privilege escalation path.

The paranoid score reaches the borderline manual-review range because local perf bugs in NMI context can be sensitive and may be reachable by unprivileged users on some systems. It should not be promoted to Important without additional evidence of memory corruption or privilege escalation.

## 5. One-sentence report phrase

AMD IBS perf handling could call perf_allow_kernel() from the IBS NMI handler while processing raw samples, allowing a local user with access to suitable perf events to trigger a fatal kernel condition and cause denial of service.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is not a demonstrated memory corruption or LPE issue, but it is a local perf/NMI kernel crash path with possible unprivileged reachability depending on perf policy.

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

Patch: perf/amd/ibs: Avoid calling perf_allow_kernel() from the IBS NMI handler [ Upstream
Commit: 2783ed2442ce69ae240b787aee6dae801cef7aec
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2783ed2442ce69ae240b787aee6dae801cef7aec

Changed files:
  arch/x86/events/amd/ibs.c
  arch/x86/events/perf_event_flags.h

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=2783ed2442ce69ae240b787aee6dae801cef7aec

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

The original Linux kernel CVE announcement for CVE-2026-53114 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53114

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: Not available
  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: 2
  Paranoid ActionableScore: 3

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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).