[CVE-2026-68458][MODERATE 7.0] binder: cache secctx size before release zeroes it [ Upstream

[CVE-2026-68458][MODERATE 7.0] binder: cache secctx size before release zeroes it [ Upstream

[AL-KERNEL]

CVE: CVE-2026-68458
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: binder: cache secctx size before release zeroes it [ Upstream
Commit: 1228926e1e4d605cc74d9e675558982a6f2cf446
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1228926e1e4d605cc74d9e675558982a6f2cf446
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68458
Analysis date: Sun, 16 Aug 2026 05:12:07 -0400
ActionableScore: 8
ActionableScore lower bound: 7
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A local Binder sender may corrupt the transaction security context by abusing an inflated scatter-gather buffer bound after `lsmctx.len` is cleared, potentially affecting LSM or SELinux based Binder authorization and requiring manual review for local privilege escalation impact.

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

The original Linux kernel CVE announcement for CVE-2026-68458 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68458

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.

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

CVE-2026-68458	MODERATE	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:L/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-284;CWE-269;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N';BEST CVSS score: '7.8';DESCR 'A Binder transaction can compute an inflated scatter gather buffer end offset because lsmctx.len is read again after security_release_secctx has cleared the LSM context structure. This allows BINDER_TYPE_PTR payload data to overlap the bytes that store the transaction security context. A local sender may therefore corrupt or spoof the security context delivered with the transaction, which can affect authorization decisions made by Binder services that consume this context. For the CVSS the PR:L is used because a local unprivileged app or process that can issue Binder transactions may be sufficient when it can reach a node using txn_security_ctx. The issue is not network reachable. Impact is at least an integrity violation in local IPC and in the worst case may support privilege escalation if a privileged service trusts the corrupted security context.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 8)  SKIP CVE-2026-68458 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	READ LINUS  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP	-	-	checked

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

ActionableScore=8
ActionableScoreLower=7

## 1. ActionableScore

* Conservative score: 7
* Paranoid score: 8
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

* Local unprivileged trigger: +1
  Binder transactions are normally reachable by local apps or local processes on Android systems, subject to Binder service exposure and policy.

* Constrained kernel buffer overwrite: +1
  The inflated `sg_buf_end_offset` lets `BINDER_TYPE_PTR` copied data overlap the already written transaction security context. This is bounded within the Binder transaction buffer, not a generic arbitrary kernel write.

* Memory layout invariant restoration: +1
  The patch restores consistency between `extra_buffers_size`, `lsmctx_aligned_size`, `security_ctx`, `sg_buf_offset`, and `sg_buf_end_offset`.

* Security-boundary bypass with practical sensitive-object access: +2
  The overwritten object is the Binder transaction security context, which is security relevant because Binder services may use it for SELinux or LSM based authorization decisions.

* Integrity impact plausible: +1
  Corrupting or spoofing the delivered transaction security context can affect local IPC authorization semantics.

* Broad/default/common subsystem exposure: +1
  Binder is a core Android IPC mechanism and commonly exposed to applications through Binder services.

* Weak LPE concern in paranoid score: +1
  Privilege escalation is plausible if a privileged Binder service trusts the corrupted security context, but the patch does not demonstrate a complete service-specific exploit chain.

## 3. Reachability analysis

A local process that can issue Binder transactions can potentially trigger the bug when communicating with a Binder node using `txn_security_ctx`. The issue is not network reachable. It is most relevant on Android or Android-like systems where Binder is enabled and local apps can interact with Binder services.

Namespaces or containers do not materially lower this below local access unless Binder devices are exposed into that environment. The important condition is whether an attacker can reach a Binder endpoint that requests transaction security context and whether copied scatter-gather data can be shaped to overlap that context.

Call-site confidence: high. The affected calculations and later `BINDER_TYPE_PTR` bounds use are described directly in the commit message and visible in the changed `binder_transaction()` path.

## 4. Severity interpretation

This is stronger than an ordinary Moderate because the corrupted buffer region is not random metadata. It is a security-sensitive LSM context passed through a core IPC path. The realistic impact is at least local integrity violation in Binder IPC, with plausible privilege escalation depending on how the receiving service uses the supplied security context.

Theoretical worst case is local privilege escalation through spoofed or corrupted Binder security context. Realistic exploitability still requires a suitable Binder target and service-side trust in that context, so the conservative score stays below the highest Critical-like range.

## 5. One-sentence report phrase

A local Binder sender may corrupt the transaction security context by abusing an inflated scatter-gather buffer bound after `lsmctx.len` is cleared, potentially affecting LSM or SELinux based Binder authorization and requiring manual review for local privilege escalation impact.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

The bug corrupts security-relevant Binder transaction metadata, not merely ordinary data or a crash-only path. Even though the overwrite is constrained, the target is an authorization context, so service-specific impact and possible local privilege escalation should be reviewed manually.

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

Patch: binder: cache secctx size before release zeroes it [ Upstream
Commit: 1228926e1e4d605cc74d9e675558982a6f2cf446
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1228926e1e4d605cc74d9e675558982a6f2cf446

Changed files:
  drivers/android/binder.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=1228926e1e4d605cc74d9e675558982a6f2cf446

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

The original Linux kernel CVE announcement for CVE-2026-68458 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68458

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:L/UI:N/S:U/C:N/I:H/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 7
  Paranoid ActionableScore: 8

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).