[CVE-2026-68349][MODERATE 7.0] wifi: carl9170: fix buffer overflow in rx_stream failover path [ Upstream

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

CVE: CVE-2026-68349
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: wifi: carl9170: fix buffer overflow in rx_stream failover path [ Upstream
Commit: 5acfa18de66b6089b81c1c0bf1a3ae3c940ec39e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5acfa18de66b6089b81c1c0bf1a3ae3c940ec39e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68349
Analysis date: Mon, 10 Aug 2026 08:55:24 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-68349 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68349

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.

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

CVE-2026-68349	MODERATE	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';*CWE-787;CWE-120;*CWE-20;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'A buffer size error in the carl9170 WiFi RX stream failover path can make carl9170_rx_stream copy the full second USB transfer length instead of only the remaining missing bytes for the failover skb. When two received chunks are close to the maximum size, the combined length can exceed the 65535 byte failover skb and trigger skb_over_panic, causing a kernel crash. For the CVSS the PR:N is used for the paranoid interpretation because an attacker may not need local user privileges if the condition can be driven through crafted wireless RX traffic reaching the affected adapter. The issue is not Internet reachable in the usual sense and is better modeled as AV:A because the attacker must be in WiFi proximity or otherwise influence the local wireless receive path. Impact is at least denial of service via kernel panic. In the paranoid score, limited confidentiality and integrity impact are kept for manual review sensitivity because the bug class is an oversized kernel buffer copy, but the visible failure path is a checked skb panic rather than a demonstrated arbitrary write primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	REMOTE OOB DANGER SIMPLEFIX NETWORK SKB LINUS KPANIC  KPANIC LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS 	NO	NO	checked

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

ActionableScore=5
ActionableScoreLower=4

1. ActionableScore
* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**

2. Signal breakdown
* Firmware-mediated external influence: +1. The malformed size relationship reaches the host through the carl9170 USB WiFi RX stream, likely mediated by device firmware and RX transfer splitting rather than a plain Internet packet path.
* Constrained kernel buffer overwrite candidate: +1. The bug is an oversized copy into an SKB, but the described failure is `skb_over_panic` before a demonstrated attacker-controlled overwrite primitive.
* Memory layout invariant restoration: +1. The patch restores consistency between `tlen`, `rx_failover_missing`, and the fixed 65535-byte failover SKB size.
* Reliable kernel crash / strong DoS: +1. The commit explicitly states that near-maximum transfers can exceed the SKB and trigger `skb_over_panic`.
* Paranoid adjacent reachability upgrade: +1. If crafted wireless traffic can reliably influence RX stream fragmentation for this adapter, the issue becomes more actionable than a local-only driver bug.
* Rare hardware / driver-specific exposure: -1 for the conservative score. carl9170 is a specific USB WiFi driver, not a broad core networking path.
* Hard or special triggering condition: -1 for the conservative score. Triggering requires the failover continuation path and two near-maximum USB transfers with the right size relationship.

3. Reachability analysis
The most plausible attacker model is an adjacent wireless attacker or a malicious/buggy USB WiFi device path influencing RX stream contents and transfer boundaries. No local user account is required in the paranoid interpretation if the condition can be driven over WiFi, but this is not ordinary AV:N Internet reachability. Namespaces and containers are not central because the vulnerable path is in a hardware RX driver. The path is only present when affected carl9170 hardware and driver support are in use, so deployment exposure is limited.

Call-site confidence: high for the immediate crash mechanism because the changed call directly caps the length passed to `skb_put_data()`. Call-site confidence is medium for remote/adjacent triggerability because the patch text does not prove that real wireless frames can reliably shape the relevant USB transfer split.

4. Severity interpretation
This behaves above an ordinary Moderate because it is an externally influenced kernel RX path with an oversized SKB copy condition and a host-wide panic. Realistically, the demonstrated impact is DoS via `skb_over_panic`, not proven privilege escalation or arbitrary memory corruption. The theoretical memory-corruption concern exists because the bug class is a buffer overflow in kernel networking driver code, but the visible primitive is constrained and checked, so Important classification is not strongly supported without additional evidence of controllable overwrite beyond the panic path.

5. One-sentence report phrase
A size handling bug in the carl9170 WiFi RX stream failover path can copy more data than the remaining failover SKB space, allowing a firmware-mediated or adjacent wireless trigger to cause `skb_over_panic` and crash the kernel.

6. Manual review recommendation
MANUAL CHECK REQUIRED.
Reason: this is a WiFi RX path buffer overflow condition with external influence and a reliable kernel panic, but the practical reachability and whether it is limited to checked DoS versus broader corruption need human confirmation.

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

Patch: wifi: carl9170: fix buffer overflow in rx_stream failover path [ Upstream
Commit: 5acfa18de66b6089b81c1c0bf1a3ae3c940ec39e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5acfa18de66b6089b81c1c0bf1a3ae3c940ec39e

Changed files:
  drivers/net/wireless/ath/carl9170/rx.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=5acfa18de66b6089b81c1c0bf1a3ae3c940ec39e

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

The original Linux kernel CVE announcement for CVE-2026-68349 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68349

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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 6.4

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: 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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).