[CVE-2026-52974][LOW] net: tls: fix strparser anchor skb leak on offload RX setup failure [ Upstream

[CVE-2026-52974][LOW] net: tls: fix strparser anchor skb leak on offload RX setup failure [ Upstream

[AL-KERNEL]

CVE: CVE-2026-52974
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: net: tls: fix strparser anchor skb leak on offload RX setup failure [ Upstream
Commit: 0c9f399b37ce22a5ed94cc51f03ed07ac7f38e32
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0c9f399b37ce22a5ed94cc51f03ed07ac7f38e32
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52974
Analysis date: Wed, 24 Jun 2026 14:34:36 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A TLS RX device offload setup failure can leak the strparser anchor skb allocated during tls_strp_init, causing a small local resource leak that may only become a DoS concern under repeated failed setup attempts.

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

The original Linux kernel CVE announcement for CVE-2026-52974 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52974

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-2026-52974	LOW	CHECK	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 'A resource leak in the TLS RX device offload setup error path can leave the strparser anchor skb allocated when tls_dev_add fails after tls_strp_init has already allocated it. This is a cleanup bug on a failed setup path and the visible primitive is a memory leak rather than UAF, OOB access, or arbitrary write. For the CVSS the PR:L is used because reliable triggering requires a local process able to create a TLS socket and attempt RX device offload setup on a suitable host. The issue is not directly network reachable because a remote peer cannot normally force this local offload configuration path by packet traffic alone. Impact is mainly denial of service through accumulated memory leakage, with low impact for a single failure and higher impact only under sustained repeated setup failures.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)	YES	REMOTE INIT LEAK ERRORPATH SKB 	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

Triggered signals:

* Local unprivileged trigger: +1
  A local process may be able to create a TLS socket and attempt RX device offload setup, depending on kernel, NIC, and TLS offload availability.

* Availability impact realistic: +1 in paranoid score only
  The leak can accumulate under repeated failed setup attempts, but a single failure leaks only a small anchor skb and does not imply immediate system-wide failure.

Negative or limiting signals:

* Rare AND difficult-to-reach subsystem/configuration: -1
  The bug is limited to the TLS RX device offload setup failure path. It requires kTLS RX offload context, suitable hardware or driver support, and a tls_dev_add failure.

Not triggered:

* Remote reachable / network-triggerable: +0
  A remote peer cannot normally force this local RX offload setup error path by packet traffic alone.

* Generic memory corruption: +0
  The patch fixes a missing free of an allocated skb anchor. There is no UAF, OOB access, double free, arbitrary write, or type confusion.

* Real lifetime corruption: +0
  This is a leak of a still-allocated object, not stale use after free or refcount lifetime corruption.

* Privilege escalation plausible: +0
  No exploit primitive for LPE is supported by the patch.

* Reliable kernel crash / strong DoS: +0
  The described impact is accumulated memory leakage, not an immediate crash or panic.

## 3. Reachability analysis

The likely trigger is a local process configuring TLS RX offload on a socket and hitting a failure in tls_dev_add after tls_strp_init allocated the anchor skb. The path is not directly reachable from the network because the remote peer does not normally control whether the local host attempts device RX offload setup. Namespaces may affect practical reachability if an untrusted workload can create suitable sockets and use TLS offload related options, but the hardware and driver dependency remains significant. This is not a default generic TLS receive path issue. It is tied to kTLS device offload and a setup failure path.

## 4. Severity interpretation

This behaves like a low-end resource leak issue rather than an Important kernel vulnerability. The theoretical worst case is local memory exhaustion after many repeated failed offload setup attempts, but the patch does not show memory corruption, object reuse, sensitive data exposure, or privilege escalation. Conservative handling should treat it as ordinary Moderate or Low-like. Paranoid handling can keep it as a borderline resource-exhaustion DoS candidate, but it should not be escalated to actionable Moderate or Important.

## 5. One-sentence report phrase

A TLS RX device offload setup failure can leak the strparser anchor skb allocated during tls_strp_init, causing a small local resource leak that may only become a DoS concern under repeated failed setup attempts.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This is a constrained cleanup bug with CWE-401/CWE-772 characteristics. There is no evidence of UAF, OOB access, arbitrary write, privilege escalation, remote triggerability, or sensitive-object exposure.

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

Patch: net: tls: fix strparser anchor skb leak on offload RX setup failure [ Upstream
Commit: 0c9f399b37ce22a5ed94cc51f03ed07ac7f38e32
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0c9f399b37ce22a5ed94cc51f03ed07ac7f38e32

Changed files:
  net/tls/tls.h
  net/tls/tls_strp.c
  net/tls/tls_sw.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=0c9f399b37ce22a5ed94cc51f03ed07ac7f38e32

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

The original Linux kernel CVE announcement for CVE-2026-52974 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52974

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).