[CVE-2026-68322][MODERATE REGULAR] rds: Fix inet6_addr_lst NULL dereference when IPv6 is disabled [ Upstream

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

CVE: CVE-2026-68322
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: rds: Fix inet6_addr_lst NULL dereference when IPv6 is disabled [ Upstream
Commit: 8e48d7ab1e01936a172ff31531904b003895fd8c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8e48d7ab1e01936a172ff31531904b003895fd8c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68322
Analysis date: Mon, 10 Aug 2026 08:43:54 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Ordinary Moderate / Low-like. Manual exposure check recommended
Manual review required: NO

Summary:
A local RDS socket bind to an IPv6 address can crash the kernel when booted with ipv6.disable=1 because RDS reaches IPv6 address-checking code after IPv6 address-list state was never initialized.

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

The original Linux kernel CVE announcement for CVE-2026-68322 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68322

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-2026-68322	MODERATE	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:N/I:N/A:H';**CWE-476;CWE-703;CWE-754;BEST CVSS score: '5.5';DESCR 'Paranoid score is not raised above the base score because the primitive is a NULL pointer dereference with no evidence of UAF, stale pointer reuse, OOB access, arbitrary write, or data exposure. Manual review is still recommended mainly to confirm local RDS socket accessibility and distribution specific module policy.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like. Manual exposure check recommended (with actual score 3)  SKIP CVE-2026-68322 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	KASAN OOB NULLPTR KERNEL_PANIC_PLUS_UAF BOOT IPV6  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Ordinary Moderate / Low-like. Manual exposure check recommended**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. The reproducer uses local `socket(PF_RDS, SOCK_SEQPACKET, 0)` plus `bind()` to an IPv6 address.
* Reliable kernel crash / strong DoS: +1. The commit shows a concrete NULL pointer dereference in `__ipv6_chk_addr_and_flags()`.
* Rare AND configuration-dependent exposure: -1. The issue requires RDS availability plus booting with `ipv6.disable=1`.

Paranoid additional signal:

* Availability impact realistic: +1. If RDS sockets are available to untrusted local users on a system booted with IPv6 disabled, the crash path appears simple and host-wide.

No added signals for:

* Generic memory corruption. This is a NULL pointer dereference, not UAF, OOB write, double-free, refcount abuse, or type confusion.
* Privilege escalation. No reclaim, stale object reuse, write primitive, callback control, or attacker-controlled replacement is shown.
* Remote reachability. The demonstrated trigger is local bind. The RDS IB receive-side checks are relevant hardening, but the supplied evidence does not justify scoring this as remotely triggerable.

## 3. Reachability analysis

A local process can trigger the shown path if it can create an RDS socket and bind it to an IPv6 address while the kernel was booted with `ipv6.disable=1`. In typical deployments, RDS is not as broadly exposed as TCP/IP core paths and may be unavailable, module-gated, blocked by policy, or absent from the product kernel. Namespaces may matter if untrusted container workloads can access PF_RDS sockets, but the patch does not show a namespace escape or privilege boundary bypass. Realistic exploitation is therefore a local DoS only under a specific configuration.

Call-site confidence: high. The commit includes the crashing call trace and a direct reproducer through `rds_bind()` -> `rds_tcp_laddr_check()` -> `ipv6_chk_addr()`.

## 4. Severity interpretation

This behaves like an ordinary Moderate local denial-of-service issue, not an Important-class vulnerability. The theoretical impact is limited by the primitive: a NULL pointer dereference caused by calling IPv6 address-checking code when IPv6 global state was never initialized. There is no evidence of UAF, stale pointer reuse, attacker-controlled memory corruption, information disclosure, or privilege escalation. The issue should not be auto-escalated solely because it is in networking code, since the trigger is local and configuration-dependent.

## 5. One-sentence report phrase

A local RDS socket bind to an IPv6 address can crash the kernel when booted with ipv6.disable=1 because RDS reaches IPv6 address-checking code after IPv6 address-list state was never initialized.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED.

Manual review should confirm whether the evaluated product enables RDS, allows untrusted local users or containers to create PF_RDS sockets, and commonly supports `ipv6.disable=1`. If PF_RDS is unavailable to untrusted users, this can be treated as low-priority local DoS.

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

Patch: rds: Fix inet6_addr_lst NULL dereference when IPv6 is disabled [ Upstream
Commit: 8e48d7ab1e01936a172ff31531904b003895fd8c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8e48d7ab1e01936a172ff31531904b003895fd8c

Changed files:
  net/rds/ib.c
  net/rds/ib_cm.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=8e48d7ab1e01936a172ff31531904b003895fd8c

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

The original Linux kernel CVE announcement for CVE-2026-68322 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68322

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).