[CVE-2026-97954][MODERATE 7.0] net/rds: fix tcp stream corruption with large pages [ Upstream

[CVE-2026-97954][MODERATE 7.0] net/rds: fix tcp stream corruption with large pages [ Upstream

[AL-KERNEL]

CVE: CVE-2026-97954
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: net/rds: fix tcp stream corruption with large pages [ Upstream
Commit: ef3565a418b8309589fe9b5df098a892c9146b06
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ef3565a418b8309589fe9b5df098a892c9146b06
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97954
Analysis date: Fri, 25 Sep 2026 08:17:47 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate
Manual review required: YES

Summary:
RDS-TCP can transmit bytes beyond the logical end of its congestion map on systems with 16K or larger pages, corrupting the protocol stream and potentially exposing unused page contents to a network peer.

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

The original Linux kernel CVE announcement for CVE-2026-97954 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97954

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.

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

CVE-2026-97954	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-97954 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-125;CWE-130;*CWE-200;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'RDS TCP can transmit bytes beyond the logical end of the 8192 byte congestion map because rds_message_map_pages assigns PAGE_SIZE to every scatterlist entry including the final partial entry. On systems with 16K or larger pages the receiver can interpret the extra bytes as later RDS message headers, corrupting the TCP RDS stream and potentially causing the connection or RDS operation to hang. For the CVSS the PR:N is selected because no authenticated or local privilege is required if an attacker can interact with the exposed RDS TCP peer. AV:A and AC:H reflect that RDS is normally used on a restricted cluster network and the issue requires a system with PAGE_SIZE greater than 8192. Confirmed impact is denial of service. Limited confidentiality or integrity impact remains plausible if bytes outside the logical congestion map are not fully initialized or affect later protocol processing, but the code does not show an OOB write, UAF, or a supported privilege escalation path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate (with actual score 5)  SKIP CVE-2026-97954 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	DANGER SIMPLEFIX KPANIC MEMORY  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP	-	-	checked

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

ActionableScore=5
ActionableScoreLower=4
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

## 1. ActionableScore

* Raw conservative score: 4
* Conservative score: 4
* Raw paranoid score: 5
* Paranoid score: 5
* No floor or cap was applied.
* Final recommended bucket: **Actionable Moderate**::

## 2. Signal breakdown

Conservative signals:

* +2 Remote/network reachability. An RDS-TCP peer receives the oversized scatterlist contents through the network protocol without requiring privileges on the affected host.
* +1 Memory-layout invariant violation. The final SG length is set to `PAGE_SIZE` instead of the bytes remaining in `total_len`.
* +1 Availability impact. Extra bytes are interpreted as subsequent RDS headers, corrupting the stream and causing the documented RDS selftest hang.
* Total: 4.

Additional paranoid signal:

* +1 Confidentiality plausible. Bytes beyond the logical 8192-byte congestion map are placed in network-visible output. Whether these bytes can contain nonzero or sensitive page contents requires inspection of all allocation and initialization paths.
* Total: 5.

Not awarded:

* No UAF, write overflow, arbitrary write, controlled reclaim, or lifetime corruption is established.
* Integrity impact was not awarded. Protocol stream corruption is demonstrated, but unauthorized modification of protected kernel or application data is not.
* Strong semantic reinterpretation was not awarded separately because the header reinterpretation is the same mechanism already counted as stream corruption, and attacker control over the extra bytes is not established.
* Reliable kernel crash was not awarded. The demonstrated result is an RDS stream or selftest hang rather than a host panic.
* No extra availability point was awarded for the same hang.
* No uncommon-subsystem or large-page penalty was applied. RDS is specialized and `PAGE_SIZE > 8192` is required, but this alone does not satisfy the strict rare-and-difficult-to-reach test.
* No LPE or Important-grade corruption leverage is established.

## 3. Reachability analysis

The evaluated attacker is an RDS-TCP network peer that can interact with an exposed RDS endpoint. Such a peer does not require host-administrator privileges on the affected system, so `HostAdminRequired=NO`.

The affected system must use a page size greater than 8192 bytes, such as 16K pages. Systems with 4K pages are unaffected. RDS-TCP must also be enabled and reachable, which generally limits exposure to cluster or data-center networks rather than the public Internet.

No namespace-scoped capability is needed for the network-peer model, but the supplied material does not establish whether all possible local setup paths are namespace-scoped. Therefore, `NamespaceScopedPrivilege=UNKNOWN`.

This is not a race. No timing window, special hardware, or repeated lifetime transition is involved.

## 4. Primitive and severity interpretation

The exact primitive is an oversized final scatterlist mapping that transmits bytes beyond the logical end of the RDS congestion map. The access may remain within the physically allocated page, so this is not established as a physical kernel OOB access or memory corruption.

The demonstrated consequence is corruption of the RDS-TCP byte stream followed by a connection or operation hang. A bounded information disclosure is technically plausible because the extra bytes leave the host over the network, but the supplied code does not establish whether the unused portion of the page is always initialized or contains sensitive data.

This is `CLASS_C`, not Class A or Class B. There is no UAF, ownership violation, write primitive, or authorization bypass. `ImportantCandidate=NO` because no Important-grade primitive is established.

`AutoDowngradeAllowed=NO` because the concrete network transmission beyond the logical buffer boundary requires manual confirmation of page initialization and disclosure potential. This preserves an Actionable Moderate result without treating the issue as an Important candidate.

## 5. One-sentence report phrase

RDS-TCP can transmit bytes beyond the logical end of its congestion map on systems with 16K or larger pages, corrupting the protocol stream and potentially exposing unused page contents to a network peer.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Review all congestion-map page allocation and initialization paths to determine whether transmitted trailing bytes can contain sensitive kernel data, and confirm how reliably an unauthenticated RDS peer can induce the affected transmission.

## 7. Call-site confidence

Call-site confidence: medium

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

Patch: net/rds: fix tcp stream corruption with large pages [ Upstream
Commit: ef3565a418b8309589fe9b5df098a892c9146b06
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ef3565a418b8309589fe9b5df098a892c9146b06

Changed files:
  net/rds/message.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=ef3565a418b8309589fe9b5df098a892c9146b06

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

The original Linux kernel CVE announcement for CVE-2026-97954 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97954

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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 6.4

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).