[CVE-2026-68379][MODERATE 7.0] tcp: fix TIME_WAIT socket reference leak on PSP policy failure [ Upstream

[CVE-2026-68379][MODERATE 7.0] tcp: fix TIME_WAIT socket reference leak on PSP policy failure [ Upstream

[AL-KERNEL]

CVE: CVE-2026-68379
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: tcp: fix TIME_WAIT socket reference leak on PSP policy failure [ Upstream
Commit: e666af5dcc905ba694745963174d232deb478c55
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e666af5dcc905ba694745963174d232deb478c55
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68379
Analysis date: Mon, 10 Aug 2026 13:12:24 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A PSP-specific TCP receive-path error can leak TIME_WAIT socket references on policy failure, allowing a network attacker with reachability to an affected PSP endpoint to cause sustained kernel memory growth and potential denial of service.

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

The original Linux kernel CVE announcement for CVE-2026-68379 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68379

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-2026-68379	MODERATE	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:N/I:N/A:H';*CWE-772;*CWE-401;**CWE-400;Other CVSS 'AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.9';DESCR 'A TCP TIME_WAIT reference leak can occur when PSP policy validation fails in the IPv4 or IPv6 receive path. The old error path dropped out without releasing the tcp_tw_bucket reference, so repeated packets that hit this state can keep TIME_WAIT objects alive and gradually consume kernel memory. For the CVSS the PR:N is used because the trigger is packet based and does not require a local account on the target when the affected TCP PSP endpoint is reachable. The issue is network reachable, but practical exploitation depends on PSP being enabled and on traffic reaching sockets in TIME_WAIT with a failing PSP policy. Impact is denial of service through resource exhaustion. For the paranoid score, the highest still defensible interpretation is A:H because sustained abuse may exhaust kernel resources, while C:N and I:N remain unchanged because the patch indicates a reference leak rather than a memory corruption primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)  SKIP CVE-2026-68379 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: 659a2899a57da59f433182eba571881884d6323e YES  NO NO unknown 	MAYBE	REMOTE SIMPLEFIX LEAK NETWORK IPV6 KPANIC 	-	-	checked

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

ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: **4**
* Paranoid score: **5**
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* **Remote reachable / network-triggerable: +2**. The bug is in IPv4 and IPv6 TCP receive paths and can be triggered by packets reaching an affected PSP-enabled TCP endpoint.
* **Common networking core path or packet-processing path: +1**. The affected code is in `tcp_v4_rcv()` and `tcp_v6_rcv()`, although the vulnerable branch is PSP-specific.
* **Availability impact realistic: +1**. Repeated failures can leak `tcp_tw_bucket` references and consume kernel memory over time.

Conservative total: **4**

Paranoid additional signal:

* **Reliable kernel crash / strong DoS: +1**. If an attacker can repeatedly drive the PSP policy failure path against TIME_WAIT sockets, sustained reference leaks may lead to system-wide resource exhaustion.

Paranoid total: **5**

Not counted:

* **No generic memory corruption**. The patch fixes a missing `inet_twsk_put()` reference release, not UAF, double-free, OOB write, or type confusion.
* **No privilege escalation signal**. There is no reclaim, overwrite, stale callback, refcount takeover, or attacker-controlled object replacement shown.
* **No confidentiality or integrity impact**. The primitive is resource retention, not disclosure or modification of protected data.
* **No rare-config subtraction in the main score**. PSP is configuration-dependent, but the affected location is still a TCP receive path, and the formula says not to heavily downgrade core networking paths solely for runtime configuration.

Call-site confidence: **high**, because both IPv4 and IPv6 receive-path call sites and the missing put operation are visible in the patch.

## 3. Reachability analysis

A remote peer can plausibly trigger the affected path by sending traffic to a PSP-enabled TCP endpoint and causing `psp_twsk_rx_policy_check()` to fail while the matching socket is in TIME_WAIT. No local account is required on the target in that network-reachable configuration, so the practical PR interpretation is **PR:N** for CVSS-style reasoning.

The important limitation is that PSP datapath support and relevant policy configuration must be enabled. This is not a generic TCP leak affecting all ordinary TCP traffic. Containers and namespaces do not materially reduce the requirement because the vulnerable path is packet-driven from outside the host when the service is exposed.

## 4. Severity interpretation

This behaves like an **actionable Moderate** issue, not an Important-class memory corruption vulnerability. The realistic impact is remote or adjacent-network resource exhaustion through leaked TIME_WAIT socket references. The theoretical worst case is kernel memory exhaustion and DoS after sustained traffic, but the patch does not support confidentiality impact, integrity impact, or privilege escalation.

The issue should not be auto-closed solely as a low resource leak because it is in TCP receive handling and may be externally triggerable when PSP is deployed.

## 5. One-sentence report phrase

A PSP-specific TCP receive-path error can leak TIME_WAIT socket references on policy failure, allowing a network attacker with reachability to an affected PSP endpoint to cause sustained kernel memory growth and potential denial of service.

## 6. Manual review recommendation

**MANUAL CHECK REQUIRED**

Reason: the issue is network-triggerable in an affected TCP configuration and can lead to sustained kernel resource exhaustion, even though it is not memory corruption and does not show privilege escalation.

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

Patch: tcp: fix TIME_WAIT socket reference leak on PSP policy failure [ Upstream
Commit: e666af5dcc905ba694745963174d232deb478c55
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e666af5dcc905ba694745963174d232deb478c55

Changed files:
  net/ipv4/tcp_ipv4.c
  net/ipv6/tcp_ipv6.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=e666af5dcc905ba694745963174d232deb478c55

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

The original Linux kernel CVE announcement for CVE-2026-68379 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68379

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:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.9

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).