[CVE-2026-72266][LOW] fbdev: vesafb: fix memory leak in vesafb_probe()

[CVE-2026-72266][LOW] fbdev: vesafb: fix memory leak in vesafb_probe()

[AL-KERNEL]

CVE: CVE-2026-72266
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: fbdev: vesafb: fix memory leak in vesafb_probe()
Commit: 124df55c7201d011a3fead2205685b6c47eae093
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=124df55c7201d011a3fead2205685b6c47eae093
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72266
Analysis date: Sun, 16 Aug 2026 06:37:54 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-72266 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72266

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: 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-2026-72266	LOW	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';*CWE-401;*CWE-772;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:N';BEST CVSS score: '2.3';DESCR 'vesafb_probe did not free the option string returned by fb_get_options after vesafb_setup consumed it. This is a small memory leak in the fbdev vesafb probe path and does not show a UAF, OOB access, arbitrary write, or other memory corruption primitive. For the CVSS the PR:H is used because triggering or influencing this path normally requires administrative control over kernel boot or device configuration. The issue is not network reachable and has no practical confidentiality or integrity impact. Availability impact is none in the base score and at most low in a conservative resource leak interpretation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0)	YES	LEAK UAF LINUS  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=0

1. ActionableScore
* Conservative score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate / Low-like**::

2. Signal breakdown
* No remote reachable signal: vesafb_probe is not network exposed.
* No local unprivileged trigger: influencing this path normally requires boot parameter or device configuration control.
* Requires admin/root/control of boot or platform configuration: -2.
* Legacy / non-default execution path: vesafb is a legacy fbdev boot/display path: -1.
* No memory corruption signal: the patch only adds kfree(option) after vesafb_setup(option).
* No real lifetime corruption: this is a missing free, not UAF, double free, stale pointer, refcount misuse, or RCU lifetime bug.
* Availability impact is not realistically actionable: the leak is small and tied to probe/setup, not an obvious repeatable unprivileged exhaustion path.
* Call-site confidence: high, because the relevant call sequence fb_get_options -> vesafb_setup -> kfree is directly present in the patch.

3. Reachability analysis
The bug is reachable during vesafb device probing, typically at boot or early platform device initialization. A practical attacker would need administrative control over kernel boot options or device configuration to influence the option string or cause the probe path to run. Namespaces and containers do not meaningfully lower the privilege requirement because this is not exposed through an ordinary per-container syscall, netlink, procfs, or device data-plane interface. The path is not network reachable and is not a common repeatedly triggerable user API.

4. Severity interpretation
This behaves like a Low-like cleanup issue rather than an actionable Moderate or Important kernel vulnerability. The demonstrated issue is a small memory leak caused by ownership transfer after fb_get_options. There is no supported UAF, OOB access, arbitrary write, type confusion, page-cache corruption, sensitive data exposure, or privilege escalation path. Theoretical resource exhaustion is not convincing because the allocation appears small and the probe path is not repeatedly triggerable by an unprivileged user.

5. One-sentence report phrase
vesafb_probe failed to free the option string returned by fb_get_options, causing a small probe-time memory leak that requires administrative or boot configuration control to influence and has no realistic confidentiality, integrity, or privilege escalation impact.

6. Manual review recommendation
NO MANUAL CHECK NEEDED. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED. This is a constrained memory leak cleanup with very low reachability and no concrete security primitive beyond negligible resource leakage.

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

Patch: fbdev: vesafb: fix memory leak in vesafb_probe()
Commit: 124df55c7201d011a3fead2205685b6c47eae093
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=124df55c7201d011a3fead2205685b6c47eae093

Commit description:

Since commit 73ce73c ("fbdev: Transfer video= option strings to
caller; clarify ownership") the string returned from fb_get_options()
is expected to be freed by the caller. But the string is not freed in
vesafb_probe(). Fix that by freeing the option string after setup.

Fixes: 73ce73c ("fbdev: Transfer video= option strings to caller; clarify ownership")
Cc: stable@vger.kernel.org
Signed-off-by: Abdun Nihaal <nihaal@cse.iitm.ac.in>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/video/fbdev/vesafb.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=124df55c7201d011a3fead2205685b6c47eae093

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

The original Linux kernel CVE announcement for CVE-2026-72266 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72266

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:L/PR:H/UI:N/S:U/C:N/I:N/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 2.3

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: 0

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).