[CVE-2026-74314][MODERATE 7.0] bpf: Cancel special fields on map value recycle [ Upstream

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

CVE: CVE-2026-74314
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: bpf: Cancel special fields on map value recycle [ Upstream
Commit: 9ea734e2cc0143d7429ab7dc0b20c85e5836183c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9ea734e2cc0143d7429ab7dc0b20c85e5836183c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74314
Analysis date: Sun, 16 Aug 2026 06:28:42 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
BPF map update/delete/recycle paths could perform full destruction of special map value fields from NMI-sensitive tracing context, causing local kernel instability and requiring manual review for possible object-lifetime side effects.

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

The original Linux kernel CVE announcement for CVE-2026-74314 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74314

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-2026-74314	MODERATE	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:L/UI:N/S:U/C:L/I:L/A:H';CWE-667;CWE-703;*CWE-664;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'BPF map update delete and recycle paths could perform full destruction of special map value fields from the context of the triggering operation. For tracing BPF programs this context can include NMI context where referenced kptr destructors, uptr unpinning, and graph root destruction are not generally safe. This can cause warnings, lockups, or kernel crashes when a map value containing such fields is replaced or recycled. For the CVSS the PR:L is used for the paranoid score because some deployments may delegate BPF or tracing capabilities to a local service account, container root, or a reduced capability user rather than full system administrator access. The issue is not network reachable and requires local ability to exercise BPF map operations with the affected special fields. Impact is at least local denial of service via kernel crash and in worst case may allow limited confidentiality or integrity impact due to unsafe kernel object lifecycle handling and should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	INIT BPF LEAK UAF HARDWARE LINUS TEST 	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Weak or indirect corruption candidate: +1
  The patch changes BPF special field destruction for referenced kptr, uptr, graph root, timer, workqueue, and task_work fields. The issue is not a proven arbitrary write or UAF reclaim primitive, but it is kernel object lifecycle handling in unsafe execution context.

* Real lifetime corruption: +1
  The old update/delete/recycle paths performed full field destruction when a map value was replaced or recycled. The fix separates reusable-value cancellation from final destruction, which indicates a real object lifetime and destructor-context bug.

* Reliable kernel crash or strong DoS: +1
  Full destruction can run from tracing/NMI context, where these destructors are not generally safe. Realistic impact is warning, lockup, deadlock, or kernel crash.

* Broad BPF map infrastructure exposure: +1
  The affected paths are array and hashtab BPF map update/delete/recycle paths, which are core BPF infrastructure.

* Requires privileged BPF access in typical deployments: -2
  In the evaluated configuration, unprivileged BPF is disabled and loading/attaching tracing BPF normally requires root or CAP_BPF/CAP_SYS_ADMIN/CAP_PERFMON style privileges.

* Conservative total: 3

Paranoid additions/adjustments:

* Availability impact realistic: +1
  If triggered, the failure mode is host-wide kernel instability rather than a process-local failure.

* Weak LPE concern: +1
  This is not a demonstrated LPE primitive, but the affected objects include referenced kernel pointers and graph-root ownership state. Unsafe destruction in NMI context is enough to keep limited C/I concern for manual review.

* Reduced-capability privileged model instead of full root equivalence: +1 relative to conservative penalty
  Some deployments delegate BPF/tracing capabilities to service accounts, container-root-like contexts, or reduced-capability operators. That is not equivalent to full host root for practical triage.

* Paranoid total: 5

## 3. Reachability analysis

The bug is locally reachable through BPF map update, delete, and recycle operations involving map values with special fields. It is not network reachable. In typical hardened or enterprise deployments, unprivileged BPF is disabled, so the trigger requires root or BPF/tracing-related capabilities.

Namespaces and containers matter only if the product delegates BPF or tracing capabilities into a reduced-privilege environment. If BPF is host-root-only, this is closer to privileged local DoS. If BPF capabilities are delegated, the issue becomes more actionable because it may cross an intended capability boundary.

Call-site confidence: high. The patch shows the affected array and hashtab update/delete/recycle call sites and the replacement of bpf_obj_free_fields() with bpf_obj_cancel_fields().

## 4. Severity interpretation

This behaves more like actionable Moderate than ordinary Moderate because it affects BPF object lifecycle handling in core map paths and involves unsafe destructor execution in NMI context. The realistic demonstrated impact is local kernel DoS. The theoretical concern is limited C/I impact from unsafe kernel object lifecycle handling, but the patch does not show attacker-controlled reclaim, arbitrary write, type confusion, or a reliable privilege escalation primitive.

It should not be treated as Strong Important on the provided evidence alone. It also should not be auto-closed as low-risk because BPF special fields and referenced kernel objects are historically sensitive lifetime-management surfaces.

## 5. One-sentence report phrase

BPF map update/delete/recycle paths could perform full destruction of special map value fields from NMI-sensitive tracing context, causing local kernel instability and requiring manual review for possible object-lifetime side effects.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the issue is privileged in typical deployments, but it touches BPF special field lifetime semantics for referenced kernel objects and changes destruction behavior across array and hashtab map recycle paths. The main expected impact is DoS, but the lifecycle context is sensitive enough to require manual security review.

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

Patch: bpf: Cancel special fields on map value recycle [ Upstream
Commit: 9ea734e2cc0143d7429ab7dc0b20c85e5836183c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9ea734e2cc0143d7429ab7dc0b20c85e5836183c

Changed files:
  include/linux/bpf.h
  kernel/bpf/arraymap.c
  kernel/bpf/hashtab.c
  kernel/bpf/syscall.c
  tools/testing/selftests/bpf/prog_tests/htab_update.c
  tools/testing/selftests/bpf/prog_tests/linked_list.c
  tools/testing/selftests/bpf/prog_tests/map_kptr.c
  tools/testing/selftests/bpf/prog_tests/refcounted_kptr.c
  tools/testing/selftests/bpf/progs/htab_update.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=9ea734e2cc0143d7429ab7dc0b20c85e5836183c

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

The original Linux kernel CVE announcement for CVE-2026-74314 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74314

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:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 5.8

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: 3
  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: NO
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).