[CVE-2026-80613][MODERATE 7.0] veth: fix NAPI leak in XDP enable error path [ Upstream

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

CVE: CVE-2026-80613
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: veth: fix NAPI leak in XDP enable error path [ Upstream
Commit: fc51373345e7e6ea73da2650cb497309c50b077a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fc51373345e7e6ea73da2650cb497309c50b077a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80613
Analysis date: Fri, 28 Aug 2026 04:45:20 -0400
ActionableScore: 7
ActionableScore lower bound: 4
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A veth XDP enable rollback bug can leave a stale NAPI object linked after partial initialization failure, causing later device teardown to access or corrupt freed queue memory and potentially resulting in a local kernel crash or UAF-based privilege escalation concern.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-80613 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80613

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-2026-80613	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	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-416;CWE-459;*CWE-672;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A use after free can occur in the veth XDP enable error path because netif_napi_add can succeed for a queue but the later xdp_rxq_info registration step can fail. The rollback loop decrements the index before its first iteration and can skip netif_napi_del for the failed queue, leaving a stale napi_struct linked in the device NAPI list. When the veth device is later destroyed, the queue memory containing that NAPI object can be freed and reused, while later NAPI list traversal may access or corrupt the reallocated memory. For the CVSS the PR:L is used because reliable triggering normally requires local ability to configure veth and XDP, such as CAP_NET_ADMIN or delegated network administration inside a namespace or container. The issue is not directly network reachable and is triggered through local control plane configuration, not by packet traffic. Impact is at least local denial of service via kernel crash and in the paranoid case may allow confidentiality or integrity impact because the patch context describes a real UAF with memory corruption risk.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 6)	YES	LEAK ERRORPATH UAF NETWORK HARDWARE KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN6 DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP	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 signals:

* Memory corruption, Strong corruption primitive: +2. The commit explicitly describes a dangling `napi_struct` left in the device NAPI list and later UAF when freed queue memory is reused.
* Real lifetime corruption: +1. This is a stale lifetime/list membership bug involving `netif_napi_add()` without matching `netif_napi_del()`.
* Reliable kernel crash / strong DoS: +1. Later device teardown can traverse the stale NAPI list entry and corrupt reused memory.
* Hard or special trigger condition: -1. The bug requires the XDP enable error path, specifically failure after `netif_napi_add()` but before full queue setup.
* Requires CAP_NET_ADMIN/CAP_BPF or equivalent in typical deployments: -2. Reliable triggering normally requires veth/XDP configuration privileges.

Paranoid additional signals:

* Local low-privilege or delegated namespace trigger: +1. In container or user namespace setups, CAP_NET_ADMIN may be delegated and should not always be treated as full host root.
* Privilege escalation plausible: +2. The UAF includes stale list traversal and corruption of reallocated memory, which is stronger than a plain NULL dereference or read-only stale pointer.
* Broad container networking exposure: +1. veth is common in container networking, although XDP attachment is not always available to untrusted users.

## 3. Reachability analysis

The bug is locally reachable through veth XDP configuration and the rollback path in `veth_enable_xdp_range()`. In a typical host configuration, this requires administrative networking privileges and possibly privileged BPF/XDP access, so the conservative score applies the CAP penalty. In containerized environments or systems with delegated network administration, a reduced-privilege root or service account may be able to exercise the path without being equivalent to full host root. The issue is not directly network reachable and is not triggered by packet traffic alone.

Call-site confidence: high. The supplied patch and commit message describe the relevant add, rollback, teardown, stale list, reuse, and UAF sequence directly.

## 4. Severity interpretation

This should not be treated as an ordinary Moderate cleanup bug. The realistic demonstrated impact is local DoS or memory corruption during teardown after a failed XDP enable path. The theoretical higher-risk concern is that stale NAPI list traversal can touch memory after the containing veth queue has been freed and reused, which makes privilege escalation plausible enough for manual review, although no controlled reclaim or working LPE primitive is demonstrated in the patch text.

## 5. One-sentence report phrase

A veth XDP enable rollback bug can leave a stale NAPI object linked after partial initialization failure, causing later device teardown to access or corrupt freed queue memory and potentially resulting in a local kernel crash or UAF-based privilege escalation concern.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch explicitly describes UAF and corruption of reallocated memory, and the practical risk depends on whether veth/XDP configuration is reachable by reduced-privilege container or namespace users in the evaluated product.

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

Patch: veth: fix NAPI leak in XDP enable error path [ Upstream
Commit: fc51373345e7e6ea73da2650cb497309c50b077a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fc51373345e7e6ea73da2650cb497309c50b077a

Changed files:
  drivers/net/veth.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=fc51373345e7e6ea73da2650cb497309c50b077a

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

The original Linux kernel CVE announcement for CVE-2026-80613 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80613

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:N/I:N/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: 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).