[CVE-2026-98222][IMPORTANT] KEYS: encrypted: fix integer overflow of datablob_len

[CVE-2026-98222][IMPORTANT] KEYS: encrypted: fix integer overflow of datablob_len

[AL-KERNEL]

CVE: CVE-2026-98222
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: NO
Patch: KEYS: encrypted: fix integer overflow of datablob_len
Commit: 1e720f63dbafc093a8f5d519f05b67724993edd4
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1e720f63dbafc093a8f5d519f05b67724993edd4
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98222
Analysis date: Fri, 09 Oct 2026 08:31:14 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-98222 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98222

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-2026-98222	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2026-98222 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=3 LEGACY=IMPORTANT RESULT=DIFF INDEPENDENT_LEGACY=IMPORTANT TEMP_KPANIC_MERGE=IMPORTANT_WINS_DISAGREEMENT PRE_MERGE_LEGACY=IMPORTANT (independent Legacy and Aegis differ; FINAL: IMPORTANT, Aegis: MODERATE_KPANIC)	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-190;CWE-131;*CWE-787;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.8';DESCR 'An integer overflow in encrypted_key_alloc can truncate the calculated datablob and payload lengths when they are stored in 16 bit fields. The truncated value causes an undersized encrypted_key_payload allocation, after which __ekey_init can copy attacker influenced key description data beyond the allocated kernel heap object. KASAN observed a slab out of bounds write of about 32760 bytes, establishing a concrete memory corruption primitive rather than a warning only condition. A local user can potentially trigger the issue through the encrypted key interface when CONFIG_ENCRYPTED_KEYS is enabled and the required key type and master key are available. For the CVSS the PR:L value is used because local user or process access is required, but full administrative privileges are not normally required merely to use a permitted keyring and create keys. The issue is not directly network reachable. Impact is at least a local denial of service via kernel crash and in the worst case may allow confidentiality or integrity impact, including possible privilege escalation, through corruption of adjacent kernel heap objects. The base score uses CIA:LLH because no arbitrary write target is demonstrated. The paranoid score uses CIA:HHH because the demonstrated large kernel heap overwrite provides a plausible path to more serious exploitation and requires manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)	MAYBE	WRITE KASAN OOB SIMPLEFIX  TEMP_KPANIC_MERGE_IMPORTANT_WINS	-	-	checked

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

ActionableScore=5
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

1. ActionableScore

* Raw conservative score: 4
* Conservative score: 5
* Raw paranoid score: 4
* Paranoid score: 5
* Applied conservative floor: 4 -> 5 under the Manual Review Safety Floor for a confirmed attacker-influenced kernel heap overwrite.
* Applied paranoid floor: 4 -> 5 for the same established primitive. No speculative exploitation bonus was added.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

Positive signals:

* +2 Strong corruption primitive. A u16 truncation produces an undersized heap allocation, followed by a confirmed slab out-of-bounds write of approximately 32760 bytes. The copied master-key description is attacker influenced.
* +1 Local unprivileged trigger. The encrypted-key type is reached through the key-management syscalls, and an ordinary user can create keys in a permitted keyring and use a user-owned master key without host-admin-equivalent privilege.
* +1 Reliable kernel crash or strong DoS. A large heap overwrite is confirmed by KASAN and can realistically cause an Oops, panic, or fatal corruption on a non-instrumented kernel.

Not awarded:

* No separate +2 strong LPE leverage. The patch establishes an attacker-influenced sequential heap overwrite but not target selection, controlled placement of an adjacent victim, arbitrary write, credential corruption, or a completed LPE chain.
* No confidentiality or integrity consequence points. No named protected victim, read-back path, or demonstrated modification of security-sensitive state is supplied.
* No extra Availability point. It would duplicate the crash consequence.
* No memory-layout-invariant point. The allocation and copy-size mismatch is the same fact already scored as the strong OOB-write primitive.
* No remote-reachability point. The vulnerable operation is local.
* No race or timing penalty. The integer truncation and subsequent overwrite are deterministic once suitable lengths are accepted.
* No rare-configuration penalty. CONFIG_ENCRYPTED_KEYS is a prerequisite, but an optional kernel configuration alone is insufficient for a negative point.
* B5-R is not established. The patch does not show an index accumulating across retries or re-entry. It instead shows a single undersized allocation caused by integer truncation. No B5-R promotion is needed because the independent confirmed attacker-influenced OOB-write primitive already qualifies as Class A.

3. Reachability analysis

The evaluated attacker is an ordinary local process using the key-management interface. The attacker must be allowed to create an encrypted key in a keyring it can write and must provide or possess a suitable master key, such as a user-owned master key. These are keyring permission requirements rather than host-administrator privileges.

The complete operation does not depend on a namespace-scoped capability, so NamespaceScopedPrivilege is NO. No separate privileged setup is established beyond a kernel built with encrypted-key support and availability of the key type. No special hardware, network exposure, race, retry loop, or timing window is required.

The supplied diff does not show all syscall call sites and parser limits, but normal keyring semantics positively support below-host-admin reachability. Product-specific key quotas, LSM policy, payload limits, or disabled encrypted-key support can reduce practical exposure without changing the primitive.

4. Primitive and severity interpretation

The exact primitive is an attacker-influenced kernel heap out-of-bounds write. Arithmetic for datablob_len and the complete payload length is truncated when stored in unsigned short fields. The truncated result controls allocation size, while __ekey_init subsequently copies data according to the larger source lengths.

This is not a UAF, repeated release, stale-object use, retry-accumulated offset, or cleanup-only fault. Active-structured-versus-fixed-stale classification is therefore not applicable.

The demonstrated consequence is corruption beyond an allocated encrypted_key_payload object, with realistic kernel crash or DoS. A possible privilege-escalation consequence is technically plausible because the overwrite reaches adjacent slab memory and includes attacker-influenced bytes, but controlled victim placement, directed overwrite, arbitrary kernel read or write, and credential manipulation are not demonstrated.

PrimitiveClass is CLASS_A because the prompt explicitly classifies an attacker-influenced OOB write and meaningful heap overwrite as a strong corruption primitive. ImportantCandidate is YES because automatic Moderate closure would discard a confirmed large kernel overwrite whose exploitation leverage remains unresolved. AutoDowngradeAllowed is NO for the same reason. The likely operational severity is Actionable Moderate at minimum, with Important classification dependent on allocator-layout and victim-control analysis.

5. One-sentence report phrase

A locally reachable integer truncation in encrypted_key_alloc causes a confirmed large attacker-influenced kernel heap out-of-bounds write, requiring mandatory review for crash, heap-object corruption, and possible privilege-escalation leverage.

6. Manual review recommendation

MANUAL CHECK REQUIRED

Review should determine the effective payload limits, controllable overwrite contents, slab-cache placement, reachable adjacent object types, repeatability under key quotas, and whether heap grooming can convert the sequential overwrite into security-sensitive object corruption.

7. Call-site confidence

Call-site confidence: medium

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

Patch: KEYS: encrypted: fix integer overflow of datablob_len
Commit: 1e720f63dbafc093a8f5d519f05b67724993edd4
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1e720f63dbafc093a8f5d519f05b67724993edd4

Commit description:

encrypted_key_alloc() stores datablob_len in a u16. It is computed from
multiple string and payload lengths. If the result exceeds U16_MAX, the
assignment truncates the allocation size. KASAN reports a 32760-byte
slab-out-of-bounds write when __ekey_init() copies the master key
description into the undersized buffer.

The total payload length stored in key->datalen is also a u16. Use
check_add_overflow() to reject values that do not fit either destination,
and use kzalloc_flex() for the flexible-array allocation.

Fixes: 7e70cb4 ("keys: add new key-type encrypted")
Cc: stable@vger.kernel.org
Assisted-by: GitHub-Copilot:claude-opus-4.6
Signed-off-by: Cen Zhang <cenzhang@linux.microsoft.com>
Signed-off-by: Francis Perron <francis@akrites.dev>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: R Nageswara Sastry <rnsastry@linux.ibm.com>
Link: https://lore.kernel.org/r/20260909153433.83117-1-cenzhang@linux.microsoft.com
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  security/keys/encrypted-keys/encrypted.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=1e720f63dbafc093a8f5d519f05b67724993edd4

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

The original Linux kernel CVE announcement for CVE-2026-98222 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98222

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:L/I:L/A:H
  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: unknown
  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: IMPORTANT
KPANIC detected for this report: NO
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).