[CVE-2026-46333][IMPORTANT] ptrace: slightly saner 'get_dumpable()' logic

[CVE-2026-46333][IMPORTANT] ptrace: slightly saner 'get_dumpable()' logic

[AL-KERNEL]

CVE: CVE-2026-46333
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: ptrace: slightly saner 'get_dumpable()' logic
Commit: 93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46333
Analysis date: Thu, 09 Jul 2026 16:26:54 -0400
ActionableScore: 7
ActionableScore lower bound: 6
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A ptrace dumpability logic flaw allowed reduced-capability uid 0 callers without `CAP_SYS_PTRACE` to pass access checks for tasks without an `mm`, potentially exposing protected task state or sensitive task-associated resources.

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

The original Linux kernel CVE announcement for CVE-2026-46333 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46333

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: IMPORTANT
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-2026-46333	IMPORTANT	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:N/A:N';CWE-863;CWE-284;*CWE-200;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.5';DESCR 'ptrace_may_access could skip dumpability based restrictions for tasks without an mm, including kernel threads and tasks after exit_mm. This allowed a uid 0 caller with matching credentials but without CAP_SYS_PTRACE to pass checks that should require stronger ptrace authority. For the CVSS the PR:L is used for the paranoid score because reduced capability root, container root, or a service account with uid 0 but without CAP_SYS_PTRACE can be a realistic attacker in practical deployments. The issue is local only and is not network reachable. Impact is primarily information disclosure through ptrace protected task details, with no direct evidence of memory corruption, arbitrary write, or kernel crash.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7) 	YES	READ INIT IMPROVEONLY  KPANIC INCREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN5 KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7	NO	YES	checked

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

ActionableScore=7
ActionableScoreLower=6

## 1. ActionableScore

* Conservative score: 6
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

* +2 Security-boundary bypass with practical sensitive-object access. `ptrace_may_access()` could incorrectly allow access when the target task had no `mm`, bypassing the intended dumpability and `CAP_SYS_PTRACE` boundary.
* +2 Sensitive task state / file-descriptor access primitive. `ptrace_may_access()` gates sensitive procfs and pidfd-style task inspection paths, so bypassing it can expose privileged process state or potentially privileged file descriptors.
* +1 Process-exit privileged resource lifetime window. The bug is specifically tied to tasks after `exit_mm()`, where `mm` disappears before all task-related protected resources are necessarily irrelevant.
* +1 Confidentiality impact plausible. The realistic impact is unauthorized inspection of protected task details, not memory corruption.
* +1 Practical exploit chain strongly implied, paranoid only. The Qualys context plus ptrace and dumpability semantics make a process-exit permission-bypass chain plausible enough for manual review.
* 0 No memory-corruption score. The patch does not show UAF, OOB write, arbitrary write, type confusion, or refcount takeover.
* 0 No full root penalty. Reduced-capability uid 0, container root, or sandboxed root without `CAP_SYS_PTRACE` is not equivalent to full host root because the bug bypasses a meaningful capability boundary.

## 3. Reachability analysis

The bug is locally reachable by a caller with matching credentials, most notably uid 0 without `CAP_SYS_PTRACE`. It is not a normal unprivileged-user bug and is not network reachable. Namespace and container setups matter because reduced-capability root or service accounts running as uid 0 may be common in hardened deployments, and the intended security model relies on capabilities still restricting ptrace-like access. The affected path is broad because `ptrace_may_access()` is a central authorization helper used beyond classic ptrace.

## 4. Severity interpretation

This is not a memory corruption vulnerability and should not be scored as LPE based on kernel overwrite primitives. It behaves as an access-control and confidentiality boundary bypass. Realistic impact is unauthorized access to protected task information and possibly sensitive task-associated objects through ptrace-gated interfaces. Because it affects capability-separated root models and was reported as a security issue, it should be treated as at least actionable Moderate and plausibly an Important candidate for manual triage.

## 5. One-sentence report phrase

A ptrace dumpability logic flaw allowed reduced-capability uid 0 callers without `CAP_SYS_PTRACE` to pass access checks for tasks without an `mm`, potentially exposing protected task state or sensitive task-associated resources.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

This is a security-boundary bypass in a central authorization helper, reported by Qualys, and the practical impact depends on procfs, pidfd, task-exit timing, and reduced-capability root deployment models.

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

Patch: ptrace: slightly saner 'get_dumpable()' logic
Commit: 93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6

Commit description:

The 'dumpability' of a task is fundamentally about the memory image of
the task - the concept comes from whether it can core dump or not - and
makes no sense when you don't have an associated mm.

And almost all users do in fact use it only for the case where the task
has a mm pointer.

But we have one odd special case: ptrace_may_access() uses 'dumpable' to
check various other things entirely independently of the MM (typically
explicitly using flags like PTRACE_MODE_READ_FSCREDS).  Including for
threads that no longer have a VM (and maybe never did, like most kernel
threads).

It's not what this flag was designed for, but it is what it is.

The ptrace code does check that the uid/gid matches, so you do have to
be uid-0 to see kernel thread details, but this means that the
traditional "drop capabilities" model doesn't make any difference for
this all.

Make it all make a *bit* more sense by saying that if you don't have a
MM pointer, we'll use a cached "last dumpability" flag if the thread
ever had a MM (it will be zero for kernel threads since it is never
set), and require a proper CAP_SYS_PTRACE capability to override.

Reported-by: Qualys Security Advisory <qsa@qualys.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  include/linux/sched.h
  kernel/exit.c
  kernel/ptrace.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=93d4ba49d18e3d7fb41a9927c2d0cca5e9dfefd6

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

The original Linux kernel CVE announcement for CVE-2026-46333 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46333

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:H/UI:N/S:U/C:L/I:N/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
  The Best / paranoid CVSS score: 5.5

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: 6
  Paranoid ActionableScore: 7

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).