[CVE-2026-97419][MODERATE REGULAR] hsr: broadcast netlink notifications in the device's net namespace [ Upstream

[CVE-2026-97419][MODERATE REGULAR] hsr: broadcast netlink notifications in the device's net namespace [ Upstream

[AL-KERNEL]

CVE: CVE-2026-97419
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: hsr: broadcast netlink notifications in the device's net namespace [ Upstream
Commit: 25b69f281cebe051a8e4ab19950a939c27ead1bc
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=25b69f281cebe051a8e4ab19950a939c27ead1bc
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97419
Analysis date: Thu, 24 Sep 2026 18:03:46 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-97419 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97419

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: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-97419	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97419 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N';*CWE-200;CWE-668;CWE-862;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '3.8';DESCR 'HSR generic netlink notifications for devices located in non initial network namespaces were incorrectly multicast to init_net. A local listener in init_net could receive ring error and node down events for HSR devices in other network namespaces. The event payload exposes limited network metadata including a peer node MAC address and a slave port interface index. For the CVSS the PR:L because an attacker needs local access and the ability to subscribe to the relevant HSR generic netlink notification group in init_net. The issue is not directly network reachable. Impact is limited confidentiality loss through a network namespace isolation bypass. No memory corruption, denial of service, or privilege escalation primitive is indicated. YES REQUIRES MANUAL CHECK';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	YES	LOCK NETWORK SKB HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS	NO	NO	checked

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

ActionableScore=2
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=NO

1. ActionableScore

* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Concrete confidentiality impact. The bug discloses peer HSR node MAC addresses and slave port interface indexes from devices belonging to another network namespace.
* +1 Cross namespace isolation bypass. HSR events belonging to a non initial network namespace are delivered to listeners in init_net, contrary to the namespace ownership of the device.
* +0 Remote reachability not established. A remote peer may potentially cause an HSR ring error or node down event, but receiving the leaked event requires a local listener in init_net.
* +0 Local unprivileged trigger not awarded. The supplied context calls the init_net recipient a privileged listener and does not show whether an ordinary local user can subscribe to the relevant HSR generic netlink multicast group.
* +0 No authorization decision bypass. The patch corrects generic netlink namespace selection. It does not show a missing capability check or an ALLOW versus DENY authorization decision.
* +0 No memory corruption, UAF, invalid free, refcount misuse, arbitrary write, or kernel crash is established.
* +0 No integrity impact or privilege escalation primitive is established.
* No negative privilege penalty is applied because host administrator requirements are not proven. The required access to the HSR generic netlink notification group is unresolved from the supplied patch.

3. Reachability analysis

The vulnerable event delivery occurs when HSR asynchronously reports ring error or node down events for an HSR device located in a non initial network namespace. Before the fix, genlmsg_multicast sends the event through the default generic netlink socket in init_net instead of the namespace associated with the HSR device.

The relevant attacker for confidentiality impact is a local process capable of subscribing to the HSR generic netlink notification group in init_net. The commit explicitly describes this as a privileged listener, but the supplied code does not show the multicast group access policy, the netlink capability checks, or whether such subscription is possible for an ordinary init_net user. Therefore HostAdminRequired is UNKNOWN rather than YES or NO.

NamespaceScopedPrivilege is NO for the disclosure recipient. The incorrect delivery target is specifically init_net, so the security relevant listening operation is not confined to the namespace containing the affected HSR device. The HSR device may exist in an attacker controlled network namespace, but that alone does not establish that the attacker can observe the leaked events in init_net.

No special hardware is required beyond use of HSR networking. HSR is a specialized redundancy protocol, but no negative niche subsystem penalty is applied because the supplied evidence does not establish that an attacker cannot reach or create the relevant HSR state.

4. Primitive and severity interpretation

The established primitive is a namespace routing and isolation failure for generic netlink multicast notifications. The wrong namespace receives limited network metadata consisting of a peer MAC address and a slave interface index.

This is not a UAF, lifetime violation, active object corruption, or stale pointer bug. It is also not a concrete authorization bypass in the strict ALLOW versus DENY sense. The observed effect is limited disclosure of metadata across an intended network namespace boundary.

The bug does not establish arbitrary access to traffic, interface configuration, credentials, packet contents, host memory, or other protected resources. It also does not establish integrity impact, denial of service, or privilege escalation.

PrimitiveClass is NONE because no Important preserving memory corruption, authorization primitive, ownership violation, or active lifetime primitive is established. ImportantCandidate is NO because the disclosed values are limited metadata and no stronger downstream consequence is shown.

AutoDowngradeAllowed is NO because the patch confirms a real cross namespace isolation failure. Although the practical impact appears low, automated closure should not discard the issue until the HSR generic netlink multicast subscription policy and init_net listener privilege boundary are checked.

5. One-sentence report phrase

HSR generic netlink notifications for devices in non initial network namespaces were incorrectly multicast to init_net, allowing an authorized init_net listener to receive limited peer MAC address and interface index metadata from another network namespace.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm the HSR generic netlink multicast group subscription permissions in init_net and determine whether an unprivileged local user, delegated service, or only a host administrator can receive these notifications.

7. Call-site confidence

Call-site confidence: medium

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

Patch: hsr: broadcast netlink notifications in the device's net namespace [ Upstream
Commit: 25b69f281cebe051a8e4ab19950a939c27ead1bc
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=25b69f281cebe051a8e4ab19950a939c27ead1bc

Changed files:
  net/hsr/hsr_netlink.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=25b69f281cebe051a8e4ab19950a939c27ead1bc

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

The original Linux kernel CVE announcement for CVE-2026-97419 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97419

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:N/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
  The Best / paranoid CVSS score: 3.8

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: unknown
  Paranoid ActionableScore: 2

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).