* [CVE-2026-99225][LOW] keys: Check the authorization payload in process keyring searches
@ 2026-11-03 3:13 21% AL-KERNEL
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From: AL-KERNEL @ 2026-11-03 3:13 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-99225
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: keys: Check the authorization payload in process keyring searches
Commit: 14fb6fad526b35a7ebd121f1dd313abe652e0aa6
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=14fb6fad526b35a7ebd121f1dd313abe652e0aa6
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99225
Analysis date: Mon, 02 Nov 2026 23:13:25 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
A request-key authorization payload validation/revocation race can cause a local kernel NULL dereference and host DoS, with complete low-privilege trigger control unresolved.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-99225 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99225
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-2026-99225 LOW https://www.kernelcve.org/list/?q=CVE-2026-99225 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=LOW RESULT=DIFF TEMP_DISTANCE_MERGE_SKIP=AEGIS_NO_POSITIVE_SEVERITY_EVIDENCE (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE_KPANIC) 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-362;CWE-367;**CWE-476;BEST CVSS score: '4.7';DESCR 'A race in search_process_keyrings_rcu allows an authorization key to pass validation before request_key_auth_revoke clears its payload pointer. A request key helper can fork a descendant that inherits the authorization key and reaches the saved requestor credential fallback while the original request completes and revokes that key. The descendant may then load a NULL authorization payload and dereference rka cred, causing a kernel oops or panic. For the CVSS the PR:L value reflects that a local user context and request key helper activity are required for reliable triggering. AC:H reflects the required interleaving between validation, helper completion, revocation, and the descendant credential search. The demonstrated primitive is a NULL pointer dereference under RCU rather than UAF or controlled memory corruption, so confidentiality and integrity remain N while availability is H. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 2 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were final reconciliation stage LOW to LOW because the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) MAYBE KASAN OOB NULLPTR LEAK LINUS V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw base score: 1.
* Conservative score: 1; no floor or cap applied.
* Raw paranoid score: 2.
* Paranoid score: 2; the supplied PR:L assessment supports a plausible low-privilege local trigger, although control of the required helper behavior is not fully established.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Reliable kernel crash/strong DoS: the demonstrated NULL `rka` dereference produced a KASAN general-protection fault and can oops or panic the kernel.
* Paranoid +1 Local low-privilege trigger: the supplied analysis identifies local-user request-key activity, but the patch does not establish who controls a helper that forks the required descendant.
* No race penalty: the descendant can be paused after validation, making the ordering potentially controllable rather than proven narrow or uncontrollable.
* No UAF or corruption score: RCU keeps the old payload allocation alive; revocation clears the payload pointer, producing a NULL dereference rather than post-free access or an OOB write.
* No authorization-bypass score: validation and payload loading are ordered incorrectly, but no mandatory DENY is shown becoming ALLOW and no protected resource is exposed.
* No confidentiality, integrity, LPE, or extra availability point is supported.
3. Reachability analysis
The path requires request-key helper execution, inherited authorization state, a forked descendant, a keyring miss, and coordinated completion/revocation. Local request-key activity is grounded, but whether an ordinary user can cause the complete helper/fork behavior without prior privileged configuration is unresolved. No namespace-scoped capability chain, special hardware, or remote path is shown.
4. Primitive and severity reading
The primitive is a race-induced NULL-pointer dereference of an authorization payload after `request_key_auth_revoke()` clears it. This is CLASS_C crash/DoS behavior, not active-object UAF, repeated release, authorization bypass, or controlled corruption. B4-PENDING does not apply. Important-grade leverage past the crash is not shown, so automatic Important preservation is unwarranted.
5. One-sentence report phrase
A request-key authorization payload validation/revocation race can cause a local kernel NULL dereference and host DoS, with complete low-privilege trigger control unresolved.
6. Manual review advice
MANUAL CHECK RECOMMENDED
Confirm whether deployed request-key helper policy lets a below-host-admin requester induce the required forked-descendant sequence.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: keys: Check the authorization payload in process keyring searches
Commit: 14fb6fad526b35a7ebd121f1dd313abe652e0aa6
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=14fb6fad526b35a7ebd121f1dd313abe652e0aa6
Commit description:
An authorization payload and its saved credentials must remain valid
while search_process_keyrings_rcu() searches the requestor's keyrings.
The function validates the authorization key, then separately loads
payload.data[0] and unconditionally reads rka->cred. Validation does
not prevent request_key_auth_revoke() from clearing the payload.
A request-key helper can assume authority and fork a descendant that
inherits the authorization key. If the descendant misses in its own
keyrings, it falls back to the saved requestor credentials. Successful
target instantiation invalidates the authorization key without clearing
the payload. After the helper exits, UMH_WAIT_PROC returns to the
requester, which calls complete_request_key() and revokes that key.
With the descendant paused after validation, the paths can interleave
as follows:
1. The descendant enters search_process_keyrings_rcu() under RCU and
key_validate() succeeds.
2. The helper instantiates the target, invalidates the authorization
key, and exits.
3. The requester resumes from UMH_WAIT_PROC, calls
complete_request_key(), and revokes the authorization key.
request_key_auth_revoke() sets its payload pointer to NULL.
4. The descendant loads NULL and dereferences rka->cred.
This NULL dereference can oops the kernel. RCU delays payload disposal
but does not prevent the pointer from being cleared.
Load the payload with dereference_key_rcu() and require a non-NULL
result before validating the authorization key and searching its saved
credentials. A non-NULL payload and its credentials remain alive for
the caller's RCU read-side section; a cleared payload skips the fallback
search and follows the existing error selection.
KASAN report as below:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
RIP: 0010:search_process_keyrings_rcu+0x32b/0x790
Cc: [email protected]
Fixes: e59428f ("keys: Move the RCU locks outwards from the keyring search functions")
Assisted-by: LLM
Signed-off-by: Cen Zhang <[email protected]>
Reviewed-by: Jarkko Sakkinen <[email protected]>
Link: https://lore.kernel.org/r/pm-key-management-objects-candidate-0004-v3-598361863b76bc25d58d@gmail.com
Signed-off-by: Jarkko Sakkinen <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
security/keys/process_keys.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=14fb6fad526b35a7ebd121f1dd313abe652e0aa6
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-99225 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99225
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: Not available
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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