[CVE-2026-80901][MODERATE 7.0] ipvs: fix the checksum validations [ Upstream

[CVE-2026-80901][MODERATE 7.0] ipvs: fix the checksum validations [ Upstream

[AL-KERNEL]

CVE: CVE-2026-80901
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: ipvs: fix the checksum validations [ Upstream
Commit: d418d73acf8be62744dc47359dfdde8c2148845d
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d418d73acf8be62744dc47359dfdde8c2148845d
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80901
Analysis date: Fri, 04 Sep 2026 13:51:48 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum**:: network reachable packet validation issue, but not a Strong Important candidate because the patch does not show memory corruption, privilege escalation, kernel crash, or sensitive data disclosure.
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-2026-80901 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80901

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.

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

CVE-2026-80901	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-80901 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L';CWE-354;CWE-345;*CWE-20;Other CVSS 'AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N';BEST CVSS score: '6.5';DESCR 'IPVS had incomplete checksum validation for ICMPv6 and related translated traffic paths. Invalid ICMPv6 packets from clients or real servers could be processed when checksum validation was missing or did not include the IPv6 pseudo header, especially when hardware did not already validate the checksum. For the CVSS the PR:N because a remote sender only needs network reachability to an IPVS virtual service and does not need a local account on the target. The issue is network reachable when IPVS is exposed to untrusted clients or real server traffic. Impact is mainly low integrity impact through acceptance or processing of packets that should fail checksum validation. Availability impact is low in the paranoid score because incorrect ICMP handling can degrade connection behavior, but the patch does not indicate memory corruption, privilege escalation, or kernel crash.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	REMOTE SKB HARDWARE IPV6 KPANIC PACKET 	NO	NO	guess

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

ActionableScore=5
ActionableScoreLower=4

1. ActionableScore
* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**:: network reachable packet validation issue, but not a Strong Important candidate because the patch does not show memory corruption, privilege escalation, kernel crash, or sensitive data disclosure.

2. Signal breakdown
* Remote reachable / network-triggerable: +2. A remote sender can influence this path by sending traffic to an exposed IPVS virtual service or related real-server traffic path.
* Integrity impact plausible: +1. Invalid ICMPv6 or related packets may be accepted or processed when checksum validation is missing or incomplete.
* Common networking packet-processing path: +1. The affected code is in IPVS/netfilter packet handling for TCP, UDP, SCTP, ICMP, and ICMPv6.
* Availability impact realistic, paranoid only: +1. Incorrect ICMP/checksum handling can plausibly degrade connection behavior or packet processing correctness, but no crash or persistent DoS is shown.
* No generic memory corruption: +0. The patch is checksum validation and offset handling, with no UAF, OOB write, double free, type confusion, or arbitrary write primitive.
* No privilege escalation plausibility: +0. There is no supported LPE chain or memory corruption sink.

3. Reachability analysis
The bug is reachable through IPVS packet processing when IPVS is configured and exposed to traffic. No local account is required for the packet sender, so the practical PR interpretation is network unauthenticated for exposed services. The affected deployment is configuration-dependent because IPVS must be in use, but IPVS is a real production load-balancing subsystem and should not be treated as rare enough to auto-close. Namespaces matter mainly for setup, since configuring IPVS normally requires elevated privileges, but triggering malformed traffic against an already configured service can be remote.

4. Severity interpretation
This behaves like an actionable Moderate issue rather than an Important-class kernel vulnerability. The strongest demonstrated impact is packet integrity validation bypass in a network-facing path, with possible low availability degradation. There is no evidence of memory corruption, kernel crash, information disclosure, privilege escalation, or shared-page ownership violation. The paranoid score is raised to 5 only because the issue is network reachable and affects packet validation in a load-balancing path.

5. One-sentence report phrase
IPVS had incomplete checksum validation for ICMPv6 and related translated traffic paths, allowing invalid packets to be processed in some MASQ or reply scenarios when hardware had not already validated the checksum.

6. Manual review recommendation
MANUAL CHECK REQUIRED. This is network reachable and deployment impact depends on IPVS mode, IPv6 use, checksum offload behavior, MASQ/tunnel configuration, and exposure to untrusted client or real-server traffic.

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

Patch: ipvs: fix the checksum validations [ Upstream
Commit: d418d73acf8be62744dc47359dfdde8c2148845d
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d418d73acf8be62744dc47359dfdde8c2148845d

Changed files:
  include/net/ip_vs.h
  net/route.h
  net/ipv6.h
  net/ip6_fib.h
  net/netfilter/nf_conntrack.h
  net/netfilter/ipvs/ip_vs_core.c
  net/netfilter/ipvs/ip_vs_proto_sctp.c
  net/netfilter/ipvs/ip_vs_proto_tcp.c
  net/netfilter/ipvs/ip_vs_proto_udp.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=d418d73acf8be62744dc47359dfdde8c2148845d

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

The original Linux kernel CVE announcement for CVE-2026-80901 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80901

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:L/PR:N/UI:N/S:U/C:N/I:L/A:N
  The Best / paranoid CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
  The Best / paranoid CVSS score: 6.5

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: 5

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).