[CVE-2026-90141][MODERATE REGULAR] ipvs: fix integer overflow in ftp helper port/address parsing [ Upstream

[CVE-2026-90141][MODERATE REGULAR] ipvs: fix integer overflow in ftp helper port/address parsing [ Upstream

[AL-KERNEL]

CVE: CVE-2026-90141
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ipvs: fix integer overflow in ftp helper port/address parsing [ Upstream
Commit: d02de9a7a7e2484da0cf37e50614840623b98a62
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d02de9a7a7e2484da0cf37e50614840623b98a62
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90141
Analysis date: Thu, 17 Sep 2026 13:33:10 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-90141 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90141

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 REGULAR
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-2026-90141	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-90141 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L';CWE-190;*CWE-20;CWE-681;Other CVSS 'AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:L';BEST CVSS score: '5.6';DESCR 'An integer overflow in the IPVS FTP helper occurs because PASV address octets are accumulated in unsigned char fields and PASV or EPSV ports are accumulated in a 16 bit value without range validation. An overlong decimal value can wrap and cause the helper to configure an FTP data connection with a truncated address or port. A malicious or compromised FTP backend can trigger the issue by returning a crafted response through an IPVS service with the FTP helper enabled. For the CVSS the PR:N value is used because no local privileges on the IPVS host are required, although the attacker must control the FTP response or the relevant network path. The realistic impact is disruption of the FTP data connection. Limited confidentiality or integrity impact is also plausible if truncation redirects a data connection to an unintended reachable endpoint. There is no demonstrated memory corruption or privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)  SKIP CVE-2026-90141 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES  NO NO unknown 	MAYBE	REMOTE OOB SIMPLEFIX NETFILTER 	-	-	checked

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

ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* No floor or cap was applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Availability impact realistic. Crafted PASV or EPSV values can produce a truncated endpoint and disrupt the FTP data connection.
* Remote reachable +2 not awarded. Traffic reaches the parser only through a previously configured IPVS FTP service and helper, and the attacker generally must control a configured FTP backend or the relevant network path.
* Memory-corruption points not awarded. The overflow truncates ordinary numeric values and does not produce an OOB access, UAF, overwrite, or invalid kernel pointer.
* Strong semantic reinterpretation not awarded. The parser produces an incorrect address or port, but no distinct active descriptor, ownership domain, pointer, or control representation is established.
* Confidentiality not awarded. No concrete path shows data from another principal being disclosed.
* Integrity not awarded. Although an incorrect endpoint is installed, the evidence does not establish modification of protected data or a meaningful authorization boundary bypass.
* Reliable kernel crash not awarded. The supplied evidence establishes data-connection misconfiguration rather than an Oops, panic, or host-wide failure.
* Common networking-core-path +1 not awarded. IPVS FTP application-helper parsing is a specialized configured path rather than a generally exercised packet-processing path.
* No race, UAF floor, resource leak, privilege escalation, or repeated lifetime mutation applies.

3. Reachability analysis

A malicious or compromised FTP backend can supply the crafted PASV or EPSV response. An on-path actor capable of modifying the established FTP control connection may also be able to provide the malformed value.

The attacker does not need host-administrator privilege after the IPVS FTP service and helper have been configured, so HostAdminRequired is NO. However, separate prior privileged setup is required to deploy the IPVS service and enable the relevant helper path. This prevents treating arbitrary Internet traffic as direct remote reachability under the scoring rule.

The supplied context does not establish whether the complete IPVS setup and trigger can be created within an attacker-controlled user and network namespace, so NamespaceScopedPrivilege is UNKNOWN. No special hardware, boot mode, or race timing is required.

4. Primitive and severity interpretation

The exact defect is unchecked arithmetic truncation while parsing decimal address octets and port values. An octet above 255 wraps in an unsigned char, while an oversized port wraps in the original 16-bit accumulator.

The resulting primitive is an attacker-influenced invalid endpoint value. It is not kernel memory corruption and does not establish active-object lifetime corruption, stale storage, UAF, OOB access, arbitrary write, or authorization bypass. PrimitiveClass is therefore CLASS_C because the demonstrated behavior is invalid connection state with service-level availability impact.

The practical consequence is failure or misdirection of an FTP data connection. Redirection to a security-sensitive endpoint is theoretically conceivable, but the supplied evidence does not show that this creates authority unavailable through an ordinary valid PASV response. There is no supported privilege-escalation path.

ImportantCandidate is NO because no Important-preserving primitive is established. AutoDowngradeAllowed is YES because the issue is a bounded protocol-parsing logic defect without unresolved kernel corruption or security-boundary leverage.

5. One-sentence report phrase

An oversized FTP PASV or EPSV address or port can wrap during IPVS helper parsing and configure a truncated data endpoint, causing incorrect or failed FTP data connections without demonstrating kernel memory corruption or privilege escalation.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm whether the affected deployment permits a crafted wrapped endpoint to reach an unintended sensitive service, but the patch evidence alone supports only limited FTP data-connection disruption.

7. Call-site confidence

Call-site confidence: medium

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

Patch: ipvs: fix integer overflow in ftp helper port/address parsing [ Upstream
Commit: d02de9a7a7e2484da0cf37e50614840623b98a62
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d02de9a7a7e2484da0cf37e50614840623b98a62

Changed files:
  net/netfilter/ipvs/ip_vs_ftp.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=d02de9a7a7e2484da0cf37e50614840623b98a62

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

The original Linux kernel CVE announcement for CVE-2026-90141 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90141

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:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:L
  The Best / paranoid CVSS vector: AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
  The Best / paranoid CVSS score: 5.6

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: 1

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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).