[CVE-2026-53009][IMPORTANT] ice: fix double-free of tx_buf skb [ Upstream

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

CVE: CVE-2026-53009
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: ice: fix double-free of tx_buf skb [ Upstream
Commit: 4c08fc2119ef0281cfa2cee007acf0a251be55f2
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4c08fc2119ef0281cfa2cee007acf0a251be55f2
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53009
Analysis date: Wed, 24 Jun 2026 12:57:46 -0400
ActionableScore: 7
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A double-free in the Intel ice TX path can leave a freed skb referenced by tx_buf after an offload failure, allowing later TX ring cleanup to free the same skb again and causing at least a local DoS with plausible memory-corruption based privilege escalation risk.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-53009 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53009

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: IMPORTANT
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-2026-53009	IMPORTANT	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-415;*CWE-416;*CWE-664;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A double free can occur in the Intel ice TX path when ice_xmit_frame_ring() stores an skb in the first tx_buf and marks it as ICE_TX_BUF_SKB, then an ice_tso() or ice_tx_csum() failure drops and frees the skb while the tx_buf still points to it. If no later packet overwrites that descriptor before the interface or TX ring is cleaned, ice_clean_tx_ring() can free the same skb again. For the CVSS the PR:L because a local user or process that can transmit traffic through an affected ice interface may reach the TX path, although reliable triggering also depends on forcing an offload error and a later cleanup window. The issue is not directly network reachable from a remote peer because the vulnerable path is local packet transmission and ring cleanup rather than receive side packet parsing. Impact is at least a local denial of service via kernel crash and in worst case may allow confidentiality or integrity impact due to double free memory corruption, so manual review is recommended.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7)	YES	REMOTE DANGER ERRORPATH UAF NETWORK SKB TEST KPANIC PACKET 	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=7
ActionableScoreLower=5

## 1. ActionableScore

* Conservative score: 5
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. A local process can normally transmit packets through the affected interface and reach the TX path, although reliable triggering depends on hitting the offload failure path.
* Generic memory corruption, strong corruption primitive: +2. The patch and commit explicitly describe a double-free of an skb.
* Real lifetime corruption: +1. The tx_buf keeps a stale skb pointer after the skb has already been freed.
* Weak LPE concern: +1. Double-free in skb lifetime handling can theoretically become more than DoS, but no attacker-controlled reclaim or overwrite primitive is shown.
* Reliable kernel crash / strong DoS: +1. The issue was reproduced with KASAN and the second free is a concrete kernel memory-safety failure.
* Hard or unreliable timing / special condition required: -1. Triggering requires ice_tso() or ice_tx_csum() failure, no later descriptor overwrite, and ring/interface cleanup before recovery.

Conservative total: 5

Paranoid additions / interpretation:

* Privilege escalation plausible: +2 instead of weak +1. In the paranoid view, skb double-free in a network driver TX path is treated as a plausible LPE candidate even without a demonstrated exploit primitive.
* Privileged kernel/device-management memory corruption path: +1. The stale pointer is later consumed during TX ring cleanup in a trusted NIC driver resource-management path.

Paranoid total: 7

## 3. Reachability analysis

The vulnerable path is local packet transmission through an Intel ice interface, followed by TX ring cleanup. It is not directly remote-network-triggerable because the bug is in the transmit path, not in RX packet parsing. A local unprivileged user may reach the TX path by sending traffic, but reliable triggering also requires an offload failure and a cleanup window before the descriptor is overwritten. Bringing the interface down is typically privileged, but similar cleanup may also occur during device reset or recovery, so PR:L is a defensible triage assumption for paranoid handling. Containers or delegated network environments can reduce the practical privilege barrier if untrusted workloads can transmit through the device or influence reset/cleanup indirectly.

## 4. Severity interpretation

This is not an ordinary Moderate crash-only bug because the primitive is an explicit double-free of an skb, which is real kernel memory lifetime corruption. Realistic exploitation is likely difficult because the failure path and cleanup timing are constrained. However, kernel skb double-free bugs historically deserve manual scrutiny because allocator reuse or stale object handling may turn a crash into privilege escalation. Conservative handling is Actionable Moderate. Paranoid handling is Strong Important candidate.

## 5. One-sentence report phrase

A double-free in the Intel ice TX path can leave a freed skb referenced by tx_buf after an offload failure, allowing later TX ring cleanup to free the same skb again and causing at least a local DoS with plausible memory-corruption based privilege escalation risk.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch fixes a concrete double-free lifetime bug in kernel networking driver code, and even though the trigger is constrained, the memory corruption primitive is strong enough to require manual security review.

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UPSTREAM PATCH SUMMARY
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Patch: ice: fix double-free of tx_buf skb [ Upstream
Commit: 4c08fc2119ef0281cfa2cee007acf0a251be55f2
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4c08fc2119ef0281cfa2cee007acf0a251be55f2

Changed files:
  drivers/net/ethernet/intel/ice/ice_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=4c08fc2119ef0281cfa2cee007acf0a251be55f2

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

The original Linux kernel CVE announcement for CVE-2026-53009 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53009

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:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7

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: 5
  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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).