[CVE-2026-46028][MODERATE 7.0] crypto: algif_aead - snapshot IV for async AEAD requests

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-46028
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: crypto: algif_aead - snapshot IV for async AEAD requests
Commit: 08ea39a556ecd39b33c2b4888861001c6706a62e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=08ea39a556ecd39b33c2b4888861001c6706a62e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46028
Analysis date: Wed, 27 May 2026 10:43:03 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: NO

Summary:
AF_ALG AEAD async requests reused mutable socket-wide IV state, allowing later socket activity to change the IV seen by an in-flight request and potentially compromising crypto correctness for local AF_ALG users.

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

The original Linux kernel CVE announcement for CVE-2026-46028 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46028

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: NO

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
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CVE-2026-46028	MODERATE	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:H/I:H/A:N';CWE-362;CWE-367;CWE-327;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N';BEST CVSS score: '6.3';DESCR 'AF_ALG AEAD async requests used the mutable socket-wide IV buffer while an operation could still be in flight. Later activity on the same socket could update ctx iv before the original AEAD request completed, so encryption or decryption could run with an IV different from the one supplied for that request. For the CVSS the PR:L is used because a local user or local service context must access AF_ALG and issue concurrent async AEAD operations. The issue is not network reachable by itself and does not involve UAF, out of bounds write, arbitrary write, or kernel privilege escalation. Impact is cryptographic correctness risk, including possible confidentiality or integrity impact for data processed through the affected AF_ALG socket, especially if IV reuse or wrong IV selection is induced.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	SIMPLEFIX LINUS  KPANIC INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK	NO	YES	checked

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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**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1
  AF_ALG sockets are local userspace crypto interfaces. A local user or service can create AEAD requests and issue async operations if AF_ALG is available.

* Local unprivileged high-control kernel data-plane API: +1
  AF_ALG allows userspace to shape crypto requests, buffers, async operation timing, and socket state at relatively high granularity.

* Confidentiality impact plausible: +1
  Wrong IV or nonce selection in AEAD can undermine confidentiality for data encrypted through the affected socket.

* Integrity impact plausible: +1
  AEAD authentication or decryption semantics can be affected if the in-flight request observes a later IV than intended.

* Broad/default/common subsystem exposure: +1
  The crypto API and AF_ALG are common kernel facilities, though AF_ALG availability and policy vary by distribution.

Subtracting signals:

* Hard or timing-dependent async race: -1
  The issue requires an in-flight async AEAD request and later socket activity changing the shared IV before completion.

Paranoid additional signal:

* Crypto misuse with security impact in local service context: +1
  If AF_ALG is used by a privileged or security-sensitive local service, IV confusion may affect data belonging to a higher-privilege context even without kernel memory corruption.

No signals apply for remote reachability, UAF, OOB write, arbitrary write, page-cache corruption, kernel privilege escalation, or direct kernel memory corruption.

## 3. Reachability analysis

The trigger is local: a process must use AF_ALG AEAD with async/AIO requests and modify socket-wide IV state while a prior request is still in flight. This does not require CAP_SYS_ADMIN in normal AF_ALG usage, but it requires local code execution and access to the AF_ALG interface.

Namespaces and containers may expose AF_ALG to unprivileged workloads depending on policy. The path is not network reachable by itself. Realistic exploitation depends on whether applications or services share AF_ALG sockets across concurrent operations in a way that lets an attacker influence the IV timing.

## 4. Severity interpretation

This is an Actionable Moderate crypto-correctness issue, not a kernel memory-corruption issue. The patch does not show UAF, OOB write, arbitrary write, or LPE.

The realistic impact is incorrect AEAD operation semantics, authentication failures, or unintended IV use for data processed through AF_ALG. The theoretical security impact can be meaningful because AEAD IV misuse may compromise confidentiality or integrity at the data-protection layer, especially in privileged service contexts.

## 5. One-sentence report phrase

AF_ALG AEAD async requests reused mutable socket-wide IV state, allowing later socket activity to change the IV seen by an in-flight request and potentially compromising crypto correctness for local AF_ALG users.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is not memory corruption or LPE, but it affects AEAD IV handling in a high-control local crypto API and can have real confidentiality or integrity consequences depending on application usage.

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

Patch: crypto: algif_aead - snapshot IV for async AEAD requests
Commit: 08ea39a556ecd39b33c2b4888861001c6706a62e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=08ea39a556ecd39b33c2b4888861001c6706a62e

Commit description:

AF_ALG AEAD AIO requests currently use the socket-wide IV buffer during
request processing.  For async requests, later socket activity can
update that shared state before the original request has fully
completed, which can lead to inconsistent IV handling.

Snapshot the IV into per-request storage when preparing the AEAD
request, so in-flight operations no longer depend on mutable socket
state.

Fixes: d887c52 ("crypto: algif_aead - overhaul memory management")
Cc: stable@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Co-developed-by: Luxing Yin <tr0jan@lzu.edu.cn>
Signed-off-by: Luxing Yin <tr0jan@lzu.edu.cn>
Tested-by: Yucheng Lu <kanolyc@gmail.com>
Signed-off-by: Douya Le <ldy3087146292@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  crypto/algif_aead.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=08ea39a556ecd39b33c2b4888861001c6706a62e

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

The original Linux kernel CVE announcement for CVE-2026-46028 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46028

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:L/I:L/A:N
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
  The Best / paranoid CVSS score: 6.3

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).