[CVE-2026-80877][LOW] afs: Fix vllist leak [ Upstream

[CVE-2026-80877][LOW] afs: Fix vllist leak [ Upstream

[AL-KERNEL]

CVE: CVE-2026-80877
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: afs: Fix vllist leak [ Upstream
Commit: 13403945c2385653e282dacda304dce2a25fdb53
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=13403945c2385653e282dacda304dce2a25fdb53
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80877
Analysis date: Fri, 04 Sep 2026 14:33:25 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-80877 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80877

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: LOW
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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

CVE-2026-80877	LOW	https://www.kernelcve.org/list/?q=CVE-2026-80877 CHECK WITH IMPACT FROM ORIG NN NONE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'AFS cell update handling can leak a newly allocated vllist when the refreshed server list is empty and the existing list is not replaced. Repeated cell updates with empty VL server results may gradually consume kernel memory and can lead to denial of service through resource exhaustion. For the CVSS the PR:L is used for the paranoid interpretation because a local user may be able to trigger AFS cell lookup or refresh behavior on systems where AFS is mounted or exposed through an automount style setup. The issue is not directly network reachable as a service on the victim. Network influence is indirect and would normally require control over DNS or cell location data used by the client. Impact is availability only, with no evidence of memory corruption, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)	YES	DISK SIMPLEFIX LEAK SKIP LINUS 	YES	NO	checked

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

ActionableScore=2
ActionableScoreLower=1

1. ActionableScore
* Conservative score: 1
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**

2. Signal breakdown
* Local unprivileged trigger: +1 in the paranoid interpretation. A local user may be able to cause AFS cell lookup or refresh behavior if AFS is mounted or exposed through automount.
* Availability impact realistic: +1 in the paranoid interpretation. Repeated empty vllist updates could gradually consume kernel memory.
* Rare AND difficult-to-reach subsystem/configuration: -1. AFS is not commonly enabled or exposed on typical systems.
* Hard or sustained abuse required: -1 for conservative scoring. A single event only leaks a small object and meaningful DoS requires repeated triggering.
* No memory corruption signal. The patch fixes a leaked reference/list object, not UAF, OOB write, double free, refcount takeover, or type confusion.
* No confidentiality or integrity signal. The described effect is resource leakage only.

3. Reachability analysis
The bug is reachable only on systems using AFS. A local user might trigger cell lookup or refresh paths if AFS mounts or automounts are available, but this is configuration dependent. It is not directly network reachable as a service on the victim. Remote influence is only indirect, for example through DNS or cell location data used by the client. Namespaces do not obviously make this broadly reachable unless AFS use is delegated into the environment.

4. Severity interpretation
This behaves like an ordinary Moderate or Low-like resource leak, not an Important-class vulnerability. The realistic impact is gradual memory consumption and possible DoS only after repeated triggering. There is no supported privilege escalation path and no concrete memory corruption primitive in the patch.

5. One-sentence report phrase
AFS cell update handling can leak an empty vllist when the refreshed server list is not installed, causing a configuration-dependent local resource exhaustion risk on systems using AFS.

6. Manual review recommendation
NO MANUAL CHECK NEEDED. This is a memory leak/resource exhaustion issue without memory corruption, network service exposure, privilege escalation, or security-boundary bypass evidence.

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

Patch: afs: Fix vllist leak [ Upstream
Commit: 13403945c2385653e282dacda304dce2a25fdb53
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=13403945c2385653e282dacda304dce2a25fdb53

Changed files:
  fs/afs/cell.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=13403945c2385653e282dacda304dce2a25fdb53

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

The original Linux kernel CVE announcement for CVE-2026-80877 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80877

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:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: 1
  Paranoid ActionableScore: 2

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).