* [CVE-2026-98711][MODERATE 7.0] wifi: cw1200: fix TX padding OOB read leaking heap data to device
@ 2026-10-19 8:17 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-19 8:17 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98711
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: wifi: cw1200: fix TX padding OOB read leaking heap data to device
Commit: 71f693a0ecccf36532dd2790f7969da6c71d5d23
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=71f693a0ecccf36532dd2790f7969da6c71d5d23
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98711
Analysis date: Mon, 19 Oct 2026 04:17:00 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES
Summary:
The cw1200 TX path can repeatedly disclose up to 511 bytes of stale kernel heap data per SDIO frame to a malicious or compromised device because the bus transfer is aligned beyond the allocated skb data without reserved and zeroed padding.
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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-98711 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98711
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-2026-98711 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98711 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=0 LEGACY=MODERATE_KPANIC RESULT=SAME (final reconciliation agrees; DECISION: both MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N';CWE-125;*CWE-200;CWE-201;Other CVSS 'AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '4.6';DESCR 'The cw1200 TX path can read beyond the end of a frame buffer because the bus transfer length is rounded up for alignment without reserving matching skb tailroom. On SDIO systems this can expose up to 511 bytes of stale kernel heap data per transmitted frame to a malicious or compromised wireless device. Repeated transmissions may allow the device to collect a substantial amount of kernel memory, although the attacker cannot directly select which heap bytes appear in the padding. For the CVSS the PR:N value is used because no authenticated host privilege is required after the attacker controls the attached device. The attack vector is AV:P because the leaked padding is delivered to the directly attached SDIO or SPI device and is not transmitted to a remote WiFi peer. Impact is an information disclosure with no supported write primitive, kernel crash, or privilege escalation path. Automated impact decision path. The original SimpleNet classifier selected IMPORTANT. The primary LLM estimated paranoid CVSS 4.6 and the production ActionableScore returned 5 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage IMPORTANT to MODERATE_KPANIC because the CVSS score, vector or bug class threshold rule was applied. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS. The independent weaker Aegis shadow evaluated CVSS 2.4 and ActionableScore 0 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is MODERATE_KPANIC.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5) MAYBE REMOTE WRITE OOB LEAK ERRORPATH NETWORK SKB HARDWARE KPANIC KPANIC LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS - - checked
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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=CONFIRMED
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw conservative score: 3
* Conservative score: 5
* Raw paranoid score: 3
* Paranoid score: 5
* Applied Class A primitive-preservation calibration: 3 -> 5. The confirmed and repeatedly observable kernel heap disclosure should not be reduced to Low solely because control of a malicious physical device is required.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::
2. Signal breakdown
Positive signals:
* +2: Confirmed externally visible heap out-of-bounds read. The aligned SDIO transfer reads beyond the valid frame buffer and sends the resulting bytes to the device.
* +1: Confidentiality impact is concrete. A bogus device can receive up to 511 bytes of stale kernel heap data per transmitted frame.
* +1: A complete disclosure chain is established. Missing skb tailroom leads to an OOB read, followed by a bus transfer to the attacker-controlled device.
* +1: Repeated TX frames permit cumulative disclosure. This increases the significance beyond a single small invalid read, although the attacker cannot directly select the leaked bytes.
* -2: Exploitation depends on control of affected CW1200 hardware or firmware. This is a specialized physical-device prerequisite.
Raw score: 2 + 1 + 1 + 1 - 2 = 3.
Important non-awarded signals:
* No OOB write, UAF, arbitrary write, controlled reclaim, callback influence, or privilege-escalation primitive is established.
* Integrity and availability points are not awarded.
* Direct network reachability is not established. The padding is transferred to the attached device and is not sent over WiFi because the WSM header retains the real frame length.
* Firmware-mediated remote compromise is not assumed.
* NEW52 B5-R does not apply because this is an OOB read rather than a retry-accumulated OOB write.
* NEW53 B3-PENDING does not apply because no shared-backing write occurs.
* V32, V33, and V34 do not apply because checksum metadata or active structured state is not corrupted.
* B4 authorization-state preservation does not apply because no DENY-to-ALLOW authorization decision changes.
3. Reachability analysis
The relevant attacker controls a bogus or compromised CW1200 device attached through SDIO or SPI. No host UID 0 identity, host capability, namespace capability, or authenticated host account is required for that device to receive padding bytes once the driver transmits frames.
The attack is not an ordinary remote WiFi attack. Normal wireless peers do not receive the padding, and the supplied evidence does not show that over-the-air traffic can compromise the device or retrieve the leaked bytes. Prior installation and operation of affected hardware is required, but no separate host-administrator action by the attacker is needed after the malicious device is present.
SDIO has the meaningful exposure because alignment can add up to 511 bytes. SPI alignment adds at most one byte and therefore has much lower practical disclosure value. There is no race or narrow timing requirement. Every suitably padded TX transfer may disclose stale memory.
4. Primitive and severity interpretation
The exact primitive is a heap out-of-bounds read with an externally observable device-facing disclosure sink. It is not merely an internal invalid read because the bus transfer carries the bytes to the attached device.
This is neither an active-object lifetime violation nor fixed stale storage used after free. No object is freed prematurely, and RealUAF is therefore NO. The bug results from a mismatch between the valid skb length and the larger bus-aligned transfer length.
PrimitiveClass is CLASS_A because repeated transfers can disclose substantial amounts of kernel heap memory to an attacker-controlled device. The demonstrated consequence is kernel information disclosure. Potential disclosure of particular keys, credentials, pointers, or other secrets remains unresolved because the attacker cannot directly choose the adjacent heap contents.
ImportantCandidate is YES because the disclosure is concrete, repeated, and crosses the host-to-device trust boundary. AutoDowngradeAllowed is NO because automatically treating this as an ordinary harmless driver defect would discard a confirmed kernel-memory disclosure primitive. This does not prove LPE, host compromise, or Critical severity.
5. One-sentence report phrase
The cw1200 TX path can repeatedly disclose up to 511 bytes of stale kernel heap data per SDIO frame to a malicious or compromised device because the bus transfer is aligned beyond the allocated skb data without reserved and zeroed padding.
6. Manual review recommendation
MANUAL CHECK REQUIRED
The disclosure primitive is confirmed and repeatable, but manual analysis is needed to evaluate realistic device control, firmware trust, affected hardware deployments, and whether sensitive heap objects can predictably become adjacent to transmitted frames.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: wifi: cw1200: fix TX padding OOB read leaking heap data to device
Commit: 71f693a0ecccf36532dd2790f7969da6c71d5d23
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=71f693a0ecccf36532dd2790f7969da6c71d5d23
Commit description:
The TX path rounds the transfer size up to the bus alignment
(align_size(), up to 511 bytes for SDIO, 1 byte for SPI) but sends
the padded length straight from the frame buffer, which has no room
reserved for the padding. cw1200_data_write() therefore reads past
the end of the frame and the bus transfer carries those bytes to the
device. A bogus device can collect up to 511 bytes of kernel heap
data per TX frame.
The RX path does not have this problem: it allocates the skb with
the aligned length (alloc_len) before reading.
Compute the exact padding with the bus align_size() callback, make
sure queued TX frames have tailroom for it, and zero the padding
bytes before the transfer so nothing past the frame is exposed.
This is not expected to change driver behavior on most cases: frame
contents and transfer sizes are unchanged, only the content of the
padding bytes (previously undefined stale memory, now zero), which
the device never reads since the WSM header carries the real frame
length. The skb expansion can only fail under memory exhaustion,
in which case the frame is dropped like on the existing error paths
of cw1200_tx().
Discovered by Atuin - Automated Vulnerability Discovery Engine.
Fixes: a910e4a ("cw1200: add driver for the ST-E CW1100 & CW1200 WLAN chipsets")
Cc: [email protected]
Assisted-by: LLM
Signed-off-by: Tianchu Chen <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Johannes Berg <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
drivers/net/wireless/st/cw1200/bh.c
drivers/net/wireless/st/cw1200/txrx.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=71f693a0ecccf36532dd2790f7969da6c71d5d23
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98711 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98711
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:P/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
The Best / paranoid CVSS vector: AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
The Best / paranoid CVSS score: 4.6
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: unknown
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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