* [CVE-2026-93824][MODERATE REGULAR] tls: reject the combination of TLS and sockmap [ Upstream
@ 2026-09-25 0:57 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-25 0:57 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-93824
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: tls: reject the combination of TLS and sockmap [ Upstream
Commit: c3d4d537337f69e405a36fa561e7292ee4148bf7
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c3d4d537337f69e405a36fa561e7292ee4148bf7
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93824
Analysis date: Thu, 24 Sep 2026 20:57:45 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93824 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93824
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 REGULAR
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-2026-93824 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-93824 CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-691;CWE-362;CWE-693;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'TLS and BPF sockmap psock integration allowed TLS crypto keys to be configured on a socket already attached to a sockmap. This unsupported combination can expose latent bugs in the TLS and sockmap data paths and may result in a local denial of service or other effects that require manual source review. For the CVSS the PR:L because a local process needs access to BPF sockmap functionality or delegated BPF capabilities. The issue is not directly network reachable because it is triggered through local socket and BPF control plane operations. Confidentiality and integrity impact are not claimed because this patch does not demonstrate an information leak or a memory corruption primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) YES REMOTE LOCK INIT SIMPLEFIX RACE LINUS LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::
No UAF, OOB access, double release, stale dereference, arbitrary write, disclosure, authorization bypass, or demonstrated crash is established by the supplied patch. The score is intentionally low despite the maintainer statement that latent bugs are exploitable because the specific exploitable primitive and consequence are not identified.
2. Signal breakdown
Conservative signals:
* +1 Explicit maintainer security concern. The commit states that the TLS and sockmap integration hides latent bugs and that they are definitely exploitable. This supports review interest, but does not establish a specific corruption primitive.
Paranoid-only signal:
* +1 Unsupported TLS and sockmap state is directly constructible through local socket and BPF control-plane operations. The patch rejects TLS key configuration if a psock is already attached. This supports an invalid-state interpretation but does not establish a specific crash or corruption consequence.
Important non-awarded signals:
* +0 Real UAF. No object free, stale reference, post-free dereference, refcount mutation, or second release is shown.
* +0 Memory corruption. No OOB read, OOB write, type confusion, arbitrary write, or controlled object replacement is demonstrated.
* +0 Reliable kernel crash or strong DoS. The commit does not provide an Oops, panic, WARN, hang, or other concrete failure mode.
* +0 Remote reachability. The vulnerable configuration is created through local socket and BPF sockmap control-plane operations. Network packet traffic alone is not shown to trigger it.
* +0 Local unprivileged trigger. Creating or attaching sockmap programs may require CAP_BPF, CAP_NET_ADMIN, CAP_SYS_ADMIN, or product-specific delegated privileges. The complete capability chain is not supplied.
* +0 Local unprivileged high-control API. The patch shows configuration of TLS keys and a psock presence check, but does not establish ordinary-user BPF load and sockmap attachment capability.
* +0 Strong or weak LPE leverage. The phrase definitely exploitable does not establish controlled reclaim, attacker-controlled replacement, callback control, directed kernel write, credential modification, or a security-boundary bypass.
* +0 Confidentiality and integrity impact. No read-back, disclosure path, protected-object access, unauthorized modification, or policy bypass is shown.
* +0 Race penalty. The commit discusses avoiding a possible parallel sockmap-addition race by rejecting TLS key configuration on psock-attached sockets. It does not establish a narrow or uncontrollable trigger race for the previously accepted unsupported configuration.
* +0 BPF privilege penalty. Host-admin-equivalent privilege is not positively established. The available evidence also does not establish below-host-admin reachability.
No floor applies. The validation-only-fix rule supports a conservative cap of 4 and paranoid cap of 5, but the actual evidence-supported scores are lower.
3. Reachability analysis
The evaluated attacker is a local process able to operate on a TCP socket and arrange for that socket to be attached to a BPF sockmap before TLS crypto keys are configured.
The complete trigger requires at least two functional stages:
* TLS socket setup through the TLS ULP and TLS setsockopt configuration path.
* Sockmap creation or use and attachment of the socket to a psock.
The patch directly confirms that a socket already in a sockmap can previously proceed to TLS key configuration. It also confirms that the reverse direction was already rejected because sk_psock_init checks inet_csk_has_ulp.
The supplied material does not establish the exact privilege boundary for complete sockmap creation, BPF program loading, map population, attachment, and trigger execution. In normal configurations, BPF sockmap use can require CAP_BPF, CAP_NET_ADMIN, CAP_SYS_ADMIN, or administrative setup. Therefore:
* HostAdminRequired is UNKNOWN, not YES, because host-admin-equivalent privilege is not proven.
* HostAdminRequired is not NO, because a complete below-host-admin trigger is not proven.
* NamespaceScopedPrivilege is UNKNOWN. The material does not show that all required BPF load, sockmap, socket attachment, and TLS configuration operations work in an attacker-created namespace without host-admin-equivalent setup.
* No prior host setup is explicitly established, but the absence of proof is not evidence that an ordinary user can create the required BPF sockmap path.
* No special hardware, boot option, or firmware prerequisite is indicated.
* The unsupported state appears achievable by an ordered local configuration sequence. A timing race is not required for the known problematic direction.
4. Primitive and severity interpretation
The exact patch-supported issue is an unsupported semantic combination of kernel TLS and BPF sockmap psock processing. Before the change, do_tls_setsockopt_conf could configure TLS crypto keys for a socket that already had an attached psock. The patch rejects this state with EINVAL after checking sk_psock under RCU protection.
This is not a demonstrated lifetime bug. There is no evidence of:
* object free followed by stale use;
* UAF;
* double put or repeated refcount mutation;
* active structured-object reuse;
* OOB access;
* attacker-controlled post-free state;
* callback or ops-table consumption;
* arbitrary or directed kernel write;
* information disclosure;
* authorization bypass;
* privilege escalation.
The stale-object categories do not apply. There is no active structured UAF and no fixed stale storage UAF. There is also no concrete repeated release or refcount operation.
The demonstrated consequence is that an unsupported TLS plus sockmap configuration was accepted. The speculative consequence is that unknown latent defects in the combined TLS and sockmap data paths could be exploitable. The commit author explicitly warns about exploitability, which justifies manual source review of the integration paths, especially sk_msg, sk_skb, TLS transmit and receive handling, redirect paths, and psock teardown interactions.
However, the patch does not establish a concrete security primitive beyond invalid-state acceptance. Therefore this is PrimitiveClass NONE rather than CLASS_A, CLASS_B, or CLASS_C. ImportantCandidate is NO because the available evidence does not establish an Important-preserving corruption, lifetime, ownership, semantic reinterpretation, or authorization primitive.
AutoDowngradeAllowed is YES because no unresolved concrete corruption primitive is identified. The issue should still receive manual review because the maintainer explicitly describes the latent integration bugs as exploitable, but it is not technically defensible to preserve Important severity from this minimal rejection patch alone.
Likely operational severity is ordinary Moderate at most unless a related patch, advisory, reproducer, crash trace, or source-path analysis identifies an actual UAF, memory corruption, privilege boundary bypass, or reliable kernel crash.
5. One-sentence report phrase
The TLS and BPF sockmap combination allowed TLS keys to be configured on a socket already attached to a psock, exposing unsupported integration paths with maintainer-reported latent exploitability, but the supplied patch does not establish a concrete memory-corruption or privilege-escalation primitive.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
The maintainer explicitly states that the TLS and sockmap integration contains exploitable latent bugs, but the supplied patch is a validation-only rejection and does not identify the underlying vulnerable primitive or attacker consequence.
7. Call-site confidence
Call-site confidence: low
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: tls: reject the combination of TLS and sockmap [ Upstream
Commit: c3d4d537337f69e405a36fa561e7292ee4148bf7
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c3d4d537337f69e405a36fa561e7292ee4148bf7
Changed files:
net/tls/tls_main.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=c3d4d537337f69e405a36fa561e7292ee4148bf7
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93824 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93824
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:N/I:N/A:H
The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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: 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: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR
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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