From: AL-KERNEL <[email protected]>
To: [email protected]
Subject: [CVE-2026-46092][LOW] wifi: rtw88: check for PCI upstream bridge existence pci_upstream_bridge() returns NULL if the device is on a root bus. If 8821CE is installed in the system with such a PCI topology, the probing routine will crash. This has probably been unnoticed as 8821CE is mostly supplied in laptops where there is a PCI-to-PCI bridge located upstream from the device. However the card might be installed on a system with different configuration. Check if the bridge does exist for the specific workaround to be applied. Found by Linux Verification Center (linuxtesting.org) with Svace static analysis tool. Fixes: 24f5e38 ("rtw88: Disable PCIe ASPM while doing NAPI poll on 8821CE") Cc: [email protected] Signed-off-by: Fedor Pchelkin <[email protected]> Acked-by: Ping-Ke Shih <[email protected]> Signed-off-by: Ping-Ke Shih <[email protected]> Link: https://patch.msgid.link/[email protected]
Date: Wed, 27 May 2026 09:56:56 -0400 [thread overview]
Message-ID: <[email protected]> (raw)
CVE: CVE-2026-46092
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: wifi: rtw88: check for PCI upstream bridge existence pci_upstream_bridge() returns NULL if the device is on a root bus. If 8821CE is installed in the system with such a PCI topology, the probing routine will crash. This has probably been unnoticed as 8821CE is mostly supplied in laptops where there is a PCI-to-PCI bridge located upstream from the device. However the card might be installed on a system with different configuration. Check if the bridge does exist for the specific workaround to be applied. Found by Linux Verification Center (linuxtesting.org) with Svace static analysis tool. Fixes: 24f5e38 ("rtw88: Disable PCIe ASPM while doing NAPI poll on 8821CE") Cc: [email protected] Signed-off-by: Fedor Pchelkin <[email protected]> Acked-by: Ping-Ke Shih <[email protected]> Signed-off-by: Ping-Ke Shih <[email protected]> Link: https://patch.msgid.link/[email protected]
Commit: eb101d2abdcccb514ca4fccd3b278dd8267374f6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eb101d2abdcccb514ca4fccd3b278dd8267374f6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46092
Analysis date: Wed, 27 May 2026 09:56:56 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO
Summary:
A NULL pointer dereference in the rtw88 PCI probe path can crash systems with Realtek 8821CE hardware on a root-bus PCI topology, but the issue is not network-triggerable and requires specific hardware or privileged device-management conditions.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-46092 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46092
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: LOW
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-2026-46092 LOW CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-754;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.2';DESCR 'A NULL pointer dereference can occur in the rtw88 PCI probe path because pci_upstream_bridge() may return NULL when the Realtek 8821CE device is attached on a root bus. The driver then checks the upstream bridge vendor for an ASPM workaround and can crash during probe on such PCI topology. For the CVSS the PR:H is used in the local paranoid score because repeated probing or driver reload normally requires administrative device management privileges, while the more realistic exposure is physical or hardware topology dependent. The issue is not network reachable and is not triggered by WiFi traffic. Impact is denial of service during device initialization only, with no evidence of memory corruption, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0) YES REMOTE DANGER SIMPLEFIX NETWORK KERNEL_PANIC_PLUS_UAF HARDWARE DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=0
## 1. ActionableScore
* Conservative score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate / Low-like**::
## 2. Signal breakdown
Triggered signals:
* Reliable kernel crash / strong DoS: +1
The driver probe can crash due to a NULL pointer dereference when `pci_upstream_bridge()` returns NULL.
* Availability impact realistic: +1
The realistic impact is a probe-time kernel crash or device initialization failure on affected PCI topology.
Subtracting signals:
* Physical-only or rare hardware-only condition: -2
Triggering depends on a Realtek 8821CE device installed with an unusual PCI topology where the device is on a root bus.
* Requires admin/root/device-management control in typical deployments: -2
Repeated or intentional triggering generally requires loading/reloading the driver, reprobe, hotplug control, or specific hardware installation. This is not reachable by ordinary WiFi traffic.
Net score is clamped to 0.
No signals apply for remote reachability, local unprivileged trigger, memory corruption, lifetime corruption, privilege escalation, sensitive-object access, or security-boundary bypass.
## 3. Reachability analysis
The bug is triggered during the PCI probe path for the `rtw88` driver, specifically for Realtek 8821CE hardware when no upstream PCI bridge exists. A normal remote attacker cannot trigger it over WiFi or the network. A local unprivileged user also does not normally control PCI topology or driver probing.
Namespaces and containers do not meaningfully lower the privilege requirement unless a container is granted unusually powerful device-management capabilities, which would already be a high-privilege configuration. The vulnerable path is only relevant when the affected hardware and topology are present.
## 4. Severity interpretation
This behaves like a Low-like reliability issue or ordinary Moderate at most. The bug is a NULL pointer dereference during device initialization, not a UAF, OOB write, type confusion, refcount bug, or controlled corruption primitive.
Theoretical impact is limited to availability. Realistic exploitation evidence supports only a topology-dependent crash during probe, with no confidentiality, integrity, or privilege-escalation concern.
## 5. One-sentence report phrase
A NULL pointer dereference in the rtw88 PCI probe path can crash systems with Realtek 8821CE hardware on a root-bus PCI topology, but the issue is not network-triggerable and requires specific hardware or privileged device-management conditions.
## 6. Manual review recommendation
NO MANUAL CHECK NEEDED
This is a hardware/topology-dependent probe-time NULL dereference with DoS-only impact and no supported memory corruption or privilege-escalation primitive.
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: wifi: rtw88: check for PCI upstream bridge existence pci_upstream_bridge() returns NULL if the device is on a root bus. If 8821CE is installed in the system with such a PCI topology, the probing routine will crash. This has probably been unnoticed as 8821CE is mostly supplied in laptops where there is a PCI-to-PCI bridge located upstream from the device. However the card might be installed on a system with different configuration. Check if the bridge does exist for the specific workaround to be applied. Found by Linux Verification Center (linuxtesting.org) with Svace static analysis tool. Fixes: 24f5e38 ("rtw88: Disable PCIe ASPM while doing NAPI poll on 8821CE") Cc: [email protected] Signed-off-by: Fedor Pchelkin <[email protected]> Acked-by: Ping-Ke Shih <[email protected]> Signed-off-by: Ping-Ke Shih <[email protected]> Link: https://patch.msgid.link/[email protected]
Commit: eb101d2abdcccb514ca4fccd3b278dd8267374f6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eb101d2abdcccb514ca4fccd3b278dd8267374f6
Changed files:
drivers/net/wireless/realtek/rtw88/pci.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=eb101d2abdcccb514ca4fccd3b278dd8267374f6
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-46092 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46092
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:H/PR:H/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS vector: AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 4.2
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: 0
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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
reply other threads:[~2026-05-27 13:56 UTC|newest]
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