[CVE-2026-97476][MODERATE 7.0] rds: filter RDS_INFO_* getsockopt by caller's netns [ Upstream

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

CVE: CVE-2026-97476
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: rds: filter RDS_INFO_* getsockopt by caller's netns [ Upstream
Commit: 093f172296d32499ffac7809629b206178776eb6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=093f172296d32499ffac7809629b206178776eb6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97476
Analysis date: Thu, 24 Sep 2026 20:20:45 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
An unprivileged local user can query RDS_INFO options from an attacker-created network namespace and disclose host-wide RDS socket and connection metadata that should be isolated to other network namespaces.

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

The original Linux kernel CVE announcement for CVE-2026-97476 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97476

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-2026-97476	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97476 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N';*CWE-200;CWE-284;CWE-668;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.5';DESCR 'The RDS_INFO_* getsockopt handlers read file scope global socket and connection lists without filtering entries by the network namespace of the calling socket. A local unprivileged user can create a fresh user namespace and network namespace, open an AF_RDS socket, and obtain metadata for RDS objects belonging to init_net or other namespaces. Exposed information can include bound and peer addresses, socket inode numbers, incoming message peer addresses, TCP sequence numbers, and RDS sequence numbers. This violates network namespace isolation and can disclose host network topology and connection state to a container or isolated process. For the CVSS the PR:L value is used because local code execution and calls to the AF_RDS getsockopt interface are required, even though no administrative capability is needed. The issue is not remotely triggerable through ordinary network traffic. Impact is limited to confidentiality because the analyzed paths only copy metadata to the caller and provide no write, memory corruption, denial of service, or direct privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)  SKIP CVE-2026-97476 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	KASAN OOB LINUS IPV6 KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP	-	-	checked

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

ActionableScore=5
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

## 1. ActionableScore

* Raw conservative score: 5
* Conservative score: 5
* Raw paranoid score: 5
* Paranoid score: 5
* No floor or cap was applied.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

## 2. Signal breakdown

Positive signals:

* +2 Concrete authorization and security-boundary bypass. RDS information handlers expose entries from other network namespaces instead of restricting results to the caller namespace.
* +1 Local unprivileged trigger. The supplied reproducer establishes that an ordinary child process can create a user namespace and network namespace, open an AF_RDS socket, and invoke the affected `getsockopt`.
* +1 Confidentiality impact. The caller receives host-wide RDS addresses, socket inode numbers, peer information, and TCP or RDS sequence numbers.
* +1 Practical exploit chain. The complete sequence from an unprivileged namespace to disclosure of `init_net` RDS metadata is demonstrated by the reproducer.

Raw score: 2 + 1 + 1 + 1 = 5.

Non-awarded signals:

* No memory-corruption or UAF signal. The affected paths copy valid metadata from insufficiently filtered global lists.
* No integrity or availability point. The patch establishes unauthorized reads, not modification, resource exhaustion, or a crash.
* No remote-reachability point. The attacker must execute local code and call `getsockopt`.
* No sensitive credential or privileged-FD theft point. Addresses, inode identifiers, and sequence metadata are exposed, but no credentials, file contents, or privileged descriptors are obtained.
* No additional cross-boundary point was stacked with the +2 authorization-boundary signal.
* No broad-subsystem point. AF_RDS availability and deployment prevalence are not sufficiently established to justify it.
* No niche-subsystem penalty. Specialization alone is not evidence of difficult reachability.

## 3. Reachability analysis

The demonstrated attacker is an ordinary local user. The complete trigger uses an attacker-created user namespace and network namespace, an unprivileged AF_RDS socket, and `getsockopt(SOL_RDS, RDS_INFO_*)`. The commit explicitly states that neither `rds_create()` nor `rds_info_getsockopt()` performs a capability check.

`HostAdminRequired=NO` is therefore positively established. `NamespaceScopedPrivilege=NO` is used because no namespaced capability is required at all, rather than because a privileged operation is authorized inside the namespace.

The RDS modules must be available, and useful disclosure requires RDS objects in another namespace. The reproducer establishes these deployment prerequisites but does not make the attack remotely network-triggerable. There is no race or timing requirement.

## 4. Primitive and severity interpretation

The exact primitive is an unauthorized cross-network-namespace read of host-wide RDS socket, message, and connection metadata. This is neither stale storage nor an active-object lifetime violation. There is no repeated release, refcount mutation, UAF, or memory corruption.

The issue is classified as `CLASS_A` because the missing namespace filter concretely bypasses an isolation boundary and changes externally visible access semantics from namespace-restricted to host-wide disclosure. The demonstrated consequence is confidentiality loss involving network topology and connection-state metadata.

No protected payload contents, arbitrary read, integrity effect, denial of service, or privilege escalation is established. The paranoid CVSS interpretation of `C:H` does not create an additional ActionableScore signal because the underlying disclosure primitive is unchanged.

`ImportantCandidate=YES` reflects the concrete unprivileged namespace-boundary bypass. `AutoDowngradeAllowed=NO` is appropriate because automatically closing it as an ordinary low-value information leak would discard the established container-to-host metadata disclosure boundary. The likely operational severity is Actionable Moderate, with manual review needed to determine whether the exposed sequence and connection metadata are especially sensitive in affected RDS deployments.

## 5. One-sentence report phrase

An unprivileged local user can query RDS_INFO options from an attacker-created network namespace and disclose host-wide RDS socket and connection metadata that should be isolated to other network namespaces.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Review deployment exposure and the sensitivity of disclosed TCP and RDS sequence metadata, because the unprivileged cross-namespace disclosure is established even though no memory corruption or privilege escalation is present.

## 7. Call-site confidence

Call-site confidence: high

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

Patch: rds: filter RDS_INFO_* getsockopt by caller's netns [ Upstream
Commit: 093f172296d32499ffac7809629b206178776eb6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=093f172296d32499ffac7809629b206178776eb6

Changed files:
  net/rds/af_rds.c
  net/rds/connection.c
  net/rds/tcp.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=093f172296d32499ffac7809629b206178776eb6

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

The original Linux kernel CVE announcement for CVE-2026-97476 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97476

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:U/C:H/I:N/A:N
  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: unknown
  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).