[CVE-2026-53077][MODERATE 7.0] net/rds: Restrict use of RDS/IB to the initial network namespace [ Upstream

[CVE-2026-53077][MODERATE 7.0] net/rds: Restrict use of RDS/IB to the initial network namespace [ Upstream

[AL-KERNEL]

CVE: CVE-2026-53077
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: net/rds: Restrict use of RDS/IB to the initial network namespace [ Upstream
Commit: 3e7f14cd5a51533404e1ae4809caab46073fb5c7
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3e7f14cd5a51533404e1ae4809caab46073fb5c7
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53077
Analysis date: Fri, 26 Jun 2026 08:27:52 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: NO

Summary:
RDS/IB could be selected or used from a non-initial network namespace even though the implementation is not namespace safe, allowing a local namespace-capable process to reach unsupported kernel networking paths with likely DoS impact and limited paranoid concern for cross-namespace state exposure.

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

The original Linux kernel CVE announcement for CVE-2026-53077 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53077

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: NO

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

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

CVE-2026-53077	MODERATE	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';CWE-284;CWE-668;CWE-703;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.6';DESCR 'RDS/IB could be selected or used from a non-initial network namespace even though the RDS/IB implementation is not namespace safe. A local user or process that can create or enter such a namespace and open RDS sockets may reach unsupported RDS/IB paths through SO_RDS_TRANSPORT or local address checks. For the CVSS the PR:L is used for the paranoid score because many systems allow unprivileged users to create user and network namespaces or to run reduced capability container workloads that can access local kernel networking APIs. The issue is not directly reachable from the external network as packet traffic alone is not enough. Impact is primarily denial of service or incorrect kernel networking state, with limited confidentiality or integrity impact kept only as a cautious triage assumption because the patch restricts an unsupported namespace path rather than fixing a clear arbitrary write primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)  SKIP CVE-2026-53077  SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	DANGER INIT SIMPLEFIX IMPROVEONLY IPV6 SYZBOT  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

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

## 2. Signal breakdown

Paranoid score signals:

* Local unprivileged trigger: +1. A local process may reach this through RDS sockets in a non-initial network namespace, especially on systems with unprivileged user namespaces or container workloads.
* Reliable kernel crash / strong DoS: +1. The patch is syzbot-reported and blocks an unsupported RDS/IB namespace path that the commit says does not work properly.
* Cross-boundary isolation/policy bypass: +1. The bug crosses the intended network namespace boundary by allowing RDS/IB outside init_net.
* Confidentiality impact plausible: +1. Paranoid only, because non-namespace-safe use of global RDS/IB state may expose wrong namespace or device-associated state, but no concrete leak primitive is shown.
* Integrity impact plausible: +1. Paranoid only, because incorrect cross-netns RDS/IB use may corrupt or affect shared kernel networking state, but no controlled write primitive is shown.
* Availability impact realistic: +1. The likely demonstrated impact is host-level crash, hang, or invalid kernel state under syzkaller-style local triggering.
* Rare/config-dependent subsystem: -1. RDS/IB depends on RDS and InfiniBand/RDMA-related configuration and is not a default common Internet-facing path.

Conservative score excludes the C:L/I:L assumptions and treats this mainly as namespace-triggered local DoS.

## 3. Reachability analysis

The bug is locally reachable, not remotely packet-triggerable by itself. The relevant entry points are RDS socket configuration via `SO_RDS_TRANSPORT` and RDS/IB local address checks from a non-initial network namespace. In typical hardened deployments, creating or managing network namespaces may require privileges, but many Linux systems allow user namespaces or container environments where a reduced-privilege user can operate inside a non-init netns. RDS/IB itself is not broadly default-enabled and usually requires RDS plus RDMA/IB support, reducing broad exposure.

## 4. Severity interpretation

This behaves more like **Actionable Moderate** than ordinary Low/Moderate because it is a namespace isolation bug in kernel networking code reported by syzbot and the fix blocks an unsupported cross-namespace RDS/IB path. It is not a clear Important-class memory corruption issue from the provided diff alone. There is no demonstrated UAF, OOB write, arbitrary write, refcount takeover, or practical LPE primitive. The paranoid score keeps limited C/I concern because namespace-unsafe global RDS/IB state deserves manual review, but realistic evidence currently points mainly to local DoS or incorrect kernel state.

## 5. One-sentence report phrase

RDS/IB could be selected or used from a non-initial network namespace even though the implementation is not namespace safe, allowing a local namespace-capable process to reach unsupported kernel networking paths with likely DoS impact and limited paranoid concern for cross-namespace state exposure.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is not a proven memory corruption or remote issue, but it is a syzbot-reported networking namespace boundary fix with paranoid CVSS-style C:L/I:L/A:H concerns, so it should not be auto-closed without checking the syzkaller reproducer and RDS/IB namespace lifetime paths.

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

Patch: net/rds: Restrict use of RDS/IB to the initial network namespace [ Upstream
Commit: 3e7f14cd5a51533404e1ae4809caab46073fb5c7
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3e7f14cd5a51533404e1ae4809caab46073fb5c7

Changed files:
  net/rds/af_rds.c
  net/rds/ib.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=3e7f14cd5a51533404e1ae4809caab46073fb5c7

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

The original Linux kernel CVE announcement for CVE-2026-53077 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53077

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:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 6.6

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).