[CVE-2026-53182][MODERATE 7.0] wifi: nl80211: reject oversized EMA RNR lists

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

CVE: CVE-2026-53182
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: wifi: nl80211: reject oversized EMA RNR lists
Commit: fc0ec2fc02dfe52c5821f36fbccf6a45df43f508
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fc0ec2fc02dfe52c5821f36fbccf6a45df43f508
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53182
Analysis date: Thu, 25 Jun 2026 05:30:33 -0400
ActionableScore: 7
ActionableScore lower bound: 4
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
Oversized EMA RNR lists in nl80211 can overflow or truncate a u8 backed element count used with flexible array allocation, creating a plausible kernel heap corruption condition reachable through privileged or delegated WiFi control plane configuration.

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

The original Linux kernel CVE announcement for CVE-2026-53182 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53182

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-2026-53182	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:H/I:H/A:H';CWE-190;CWE-681;*CWE-787;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H';BEST CVSS score: '7.8';DESCR 'Oversized EMA RNR element lists in nl80211 can make the parsed element count exceed the u8 backed cfg80211_rnr_elems cnt field. Because this count is tied to flexible array allocation and later parsing, truncation or wraparound can create a size mismatch and a possible kernel heap memory corruption condition. For the CVSS the PR:L is used for the paranoid score because CAP_NET_ADMIN or equivalent nl80211 control can be delegated to a container root or service account rather than full host root. The issue is local through the nl80211 control plane and is not directly network reachable through WiFi traffic. Impact can include denial of service and potentially confidentiality or integrity impact due to the memory corruption class, so manual review is recommended.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 6)	YES	REMOTE SIMPLEFIX KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS KPANIC DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN7	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=7
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: **4**
* Paranoid score: **7**
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

### Conservative score signals

* **Memory corruption, weak or indirect corruption candidate: +1**
  The patch fixes a count overflow or truncation risk where a parsed element count is stored in a `u8` backed field and is tied to flexible array allocation or later parsing.

* **Constrained kernel buffer or allocation size mismatch concern: +1**
  The primitive is not shown as an attacker controlled arbitrary write, but the count mismatch can plausibly desynchronize allocation size and element handling.

* **Availability impact realistic: +1**
  A malformed oversized netlink attribute list could plausibly trigger kernel memory corruption or crash in the nl80211 configuration path.

* **Local high control netlink parsing surface: +1**
  The attacker can shape nested `NL80211_ATTR_EMA_RNR_ELEMS` attributes and influence parser counts and allocation related state.

* **Requires CAP_NET_ADMIN in typical deployments: -2**
  nl80211 AP configuration is normally a privileged control plane operation.

* **Broad/common subsystem exposure: +1**
  nl80211 and cfg80211 are common on WiFi capable Linux systems, although this specific EMA RNR AP path is configuration dependent.

Conservative total: **4**

### Paranoid score signals

* **Memory corruption, strong corruption primitive: +2**
  The count is stored in a `u8` backed structure field and used in flexible array sizing or parsing logic. Oversized input can plausibly cause truncation or wraparound and a heap object size mismatch.

* **Weak LPE concern: +1**
  A kernel heap allocation mismatch in a user controlled netlink parser may be exploitable beyond DoS, but no reclaim, arbitrary write, callback control, or type confusion is demonstrated.

* **Local unprivileged or reduced privilege trigger under delegation: +1**
  In hardened or containerized environments, `CAP_NET_ADMIN` or WiFi management may be delegated to a service account or container root rather than full host root.

* **Local high control netlink parsing surface: +1**
  Nested attributes give relatively fine grained control over parser state and object sizing.

* **Confidentiality impact plausible: +1**
  Plausible only in the paranoid interpretation due to kernel heap corruption potential.

* **Integrity impact plausible: +1**
  Plausible only in the paranoid interpretation due to possible heap overwrite or object corruption.

* **Availability impact realistic: +1**
  Kernel crash is a realistic outcome for count truncation leading to malformed allocation or parsing state.

Paranoid total: **8**, reduced to **7** to avoid overcounting the same allocation mismatch as both strong corruption and multiple impact signals without a demonstrated overwrite target.

## 3. Reachability analysis

The trigger is local through the nl80211 control plane, not remote through received WiFi frames. In normal deployments, changing AP or EMA RNR configuration requires `CAP_NET_ADMIN`, usually via host root, NetworkManager, hostapd, or another privileged WiFi management component.

Namespaces and containers may matter if WiFi management or `CAP_NET_ADMIN` is delegated to a reduced privilege account, container root, or service. That makes `PR:L` defensible for a paranoid score, but conservative scoring should still treat the usual path as privileged.

The path is not universally active by default. It depends on WiFi/cfg80211 support and use of EMA RNR AP configuration, but nl80211 itself is a common kernel interface.

## 4. Severity interpretation

This is not an ordinary resource leak or pure validation cleanup. The patch prevents an oversized count from exceeding a `u8` backed field that is connected to flexible array allocation and parser state, which is a plausible kernel heap corruption pattern.

Realistic exploitation evidence is limited because the patch does not show an arbitrary write, controlled reclaim, callback overwrite, or demonstrated privilege escalation path. Conservative handling is therefore borderline manual review. Paranoid handling is a strong Important candidate because count truncation plus flexible array sizing in a user controlled kernel parser is a historically risky pattern.

## 5. One-sentence report phrase

Oversized EMA RNR lists in nl80211 can overflow or truncate a u8 backed element count used with flexible array allocation, creating a plausible kernel heap corruption condition reachable through privileged or delegated WiFi control plane configuration.

## 6. Manual review recommendation

**MANUAL CHECK REQUIRED**

Reason: the patch shows a concrete integer truncation and allocation sizing mismatch pattern in a user controlled netlink parser, with plausible memory corruption impact even though a full LPE primitive is not demonstrated.

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

Patch: wifi: nl80211: reject oversized EMA RNR lists
Commit: fc0ec2fc02dfe52c5821f36fbccf6a45df43f508
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fc0ec2fc02dfe52c5821f36fbccf6a45df43f508

Commit description:

nl80211_parse_rnr_elems() stores the parsed element count in a
u8-backed cfg80211_rnr_elems::cnt field and uses that count to size
the flexible array allocation.

Reject nested NL80211_ATTR_EMA_RNR_ELEMS input once the count reaches
255, before incrementing it again. This keeps the parser aligned with
the data structure it fills and matches the existing bound check used
by nl80211_parse_mbssid_elems().

Fixes: dbbb27e ("cfg80211: support RNR for EMA AP")
Cc: stable@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Zhengchuan Liang <zcliangcn@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Assisted-by: Codex:gpt-5.4
Signed-off-by: Yuqi Xu <xuyuqiabc@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Link: https://patch.msgid.link/20260529152542.1412734-1-n05ec@lzu.edu.cn
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/wireless/nl80211.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=fc0ec2fc02dfe52c5821f36fbccf6a45df43f508

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

The original Linux kernel CVE announcement for CVE-2026-53182 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53182

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:H/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 7

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).