* [CVE-2026-80914][MODERATE 7.0] Bluetooth: ISO: fix use-after-free of listener socket in iso_conn_ready
@ 2026-09-09 17:24 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-09 17:24 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-80914
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: Bluetooth: ISO: fix use-after-free of listener socket in iso_conn_ready
Commit: 2387cd06a2c0b416f05028b02bba1089f54c28d9
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2387cd06a2c0b416f05028b02bba1089f54c28d9
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80914
Analysis date: Wed, 09 Sep 2026 13:24:11 -0400
ActionableScore: 6
ActionableScore lower bound: 5
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80914 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80914
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: YES
A detailed explanation of the methodology and priority rules is included
at the end of this message.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-80914 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-80914 CHECK WITH IMPACT FROM ORIG NN MODERATE 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:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A use after free can occur in the Bluetooth ISO listener path because iso_conn_ready can create and link a child socket after the parent listener socket has been closed concurrently. The race window is between iso_get_sock and lock_sock, where the listener may stop being a valid listening socket while iso_conn_ready still proceeds with child socket setup. A later child disconnect can dereference the dangling parent pointer through the accept queue cleanup path and trigger kernel memory corruption or a crash. For the CVSS the PR:L is used because reliable triggering normally requires a local user or local process able to operate Bluetooth ISO sockets or influence a Bluetooth service that owns such sockets. The issue is not a normal IP network reachable bug, but Bluetooth activity may be part of the trigger environment. Impact is at least local denial of service via kernel crash and in the paranoid case may include confidentiality and integrity impact due to a real use after free primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 6) YES REMOTE DANGER UAF NETWORK KPANIC KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFDH YES NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=6
ActionableScoreLower=5
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
1. ActionableScore
* Raw conservative score: 4
* Conservative score: 5. Applied Real UAF FLOOR 5 because this is a below-host-admin active structured socket lifetime UAF with stale parent use in later disconnect processing.
* Raw paranoid score: 6
* Paranoid score: 6. No cap or additional floor changed the paranoid score.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::
2. Signal breakdown
Conservative signals:
* +2 Real UAF / active lifetime violation. The listener socket can be closed after iso_get_sock() but before lock_sock(), and the child socket can remain linked to a parent whose lifetime has ended.
* +1 Reliable kernel crash / strong DoS. Later child disconnect reaches iso_chan_del() and bt_accept_unlink() with a dangling parent pointer, which supports kernel fault or crash.
* +1 Local below-host-admin trigger. The vulnerable object is a Bluetooth ISO socket controlled through a local socket lifecycle. The supplied prior triage uses PR:L rather than host-admin.
* +1 Attacker-influenced active-object lifetime manipulation. The relevant lifecycle is listener creation, concurrent close, child creation, and later child disconnect, all tied to socket state transitions.
* -1 Hard race / timing. The key window is specifically between iso_get_sock() and lock_sock(), so conservative scoring accounts for a narrow concurrency window.
Paranoid additional signal:
* +1 Structured stale-object exploitation leverage. The stale parent is an active socket object and later cleanup uses the dangling parent for accept queue and parent field processing, which is more meaningful than a simple immediate NULL dereference.
Important non-awarded signals:
* +2 Strong exploitation leverage not awarded. Controlled reclaim, attacker-shaped replacement object, arbitrary read/write, callback control, or demonstrated LPE is not established.
* Concrete repeated release/refcount +1 not awarded. The patch establishes a stale parent dereference and accept queue use, but does not concretely show a second lifetime/refcount mutation on the exact same dangling parent reference.
* Paranoid repeated-refcount +1 not awarded. There is no confirmed second write-like refcount mutation through already freed storage.
* Confidentiality and integrity bonuses are not separately awarded. They remain unresolved consequences of the UAF, not demonstrated primitives.
* Extra Availability not awarded. The same crash is already counted once.
* Remote IP/network reachability not awarded. Bluetooth activity may be part of the trigger environment, but this is not a normal remotely reachable TCP/IP packet-processing bug.
Repeated release/refcount checklist:
* First release can end lifetime: yes, the close path can drop the list reference and iso_conn_ready() later drops its reference.
* Exact same reference survives into second lifetime mutation: not established.
* Second operation is a real lifetime/refcount mutation: not established from supplied evidence.
* Dedicated +1 Concrete repeated release/refcount awarded: no.
* Paranoid repeated-refcount leverage +1 awarded: no.
* FLOOR 5 applied: yes, but due to active structured UAF surface below host admin, not due to repeated release/refcount.
3. Reachability analysis
The evaluated attacker is a local below-host-admin actor able to operate or influence Bluetooth ISO socket state. The likely trigger involves a listener socket, a concurrent listener close, ISO connection readiness, child socket creation, and later child disconnect.
Host-admin-equivalent privilege is not positively established in the supplied material. Therefore HostAdminRequired=NO. If a specific distribution gates BTPROTO_ISO creation or the needed Bluetooth operations behind host-admin-only policy, the product-specific score may be lower.
Namespace-scoped privilege is unresolved. The patch uses socket/network context, but the supplied evidence does not prove that the complete Bluetooth ISO trigger chain is available inside attacker-created namespaces. Therefore NamespaceScopedPrivilege=UNKNOWN.
Prior setup may require Bluetooth ISO support and relevant Bluetooth controller or emulated environment. This is a feature and hardware/context prerequisite, but not enough by itself to apply a rare-hardware or host-admin penalty. The race is narrow, but repeated attempts through socket lifecycle manipulation appear plausible.
4. Primitive and severity interpretation
The exact primitive is a race-induced use-after-free of a Bluetooth ISO listener socket. The stale object is an active structured kernel socket object, not fixed stale storage. The child socket may be linked to a parent listener that has already been closed and freed. A later child disconnect then uses the dangling parent pointer in accept queue cleanup and parent field dereference paths.
This is not merely a WARN or invalid state. It is a real lifetime bug with a stale structured object crossing from connection setup into later disconnect cleanup. The demonstrated consequence is kernel crash or DoS. The speculative consequence is broader kernel memory corruption or privilege escalation if heap reuse and stale socket field consumption can be shaped, but controlled reclaim and arbitrary kernel read/write are not demonstrated.
PrimitiveClass=CLASS_B because a real kernel lifetime/corruption primitive exists, but CLASS_A strength is not established. ImportantCandidate=YES because the stale object is an active socket object and the exploitation leverage beyond crash remains unresolved. AutoDowngradeAllowed=NO because automatically closing this as ordinary Moderate would discard a concrete active-object UAF with meaningful unresolved lifetime-corruption leverage.
Likely operational severity is Actionable Moderate at minimum, with Strong Important review justified if the Bluetooth ISO socket path is reachable by ordinary local users or exposed through a local Bluetooth service.
5. One-sentence report phrase
A race in Bluetooth ISO iso_conn_ready() can link a child socket to a listener socket that was concurrently closed and freed, causing a later disconnect to dereference a dangling parent pointer and potentially crash the kernel.
6. Manual review recommendation
MANUAL CHECK REQUIRED
Reason: this is a real active structured socket UAF with unresolved post-lifetime exploitation leverage, below-host-admin reachability is plausible, and automatic downgrade would risk missing an Important-class local kernel vulnerability.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: Bluetooth: ISO: fix use-after-free of listener socket in iso_conn_ready
Commit: 2387cd06a2c0b416f05028b02bba1089f54c28d9
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2387cd06a2c0b416f05028b02bba1089f54c28d9
Commit description:
iso_conn_ready() looks up the BIS listener socket with iso_get_sock(),
which takes a reference, and then, without re-checking its state,
creates a child socket from it:
parent = iso_get_sock(hdev, ...);
if (!parent)
return;
lock_sock(parent);
sk = iso_sock_alloc(sock_net(parent), NULL, BTPROTO_ISO, ...);
...
iso_chan_add(conn, sk, parent);
...
release_sock(parent);
sock_put(parent);
If the listener socket is closed concurrently, between iso_get_sock()
and lock_sock(), the reference taken by iso_get_sock() may be the last
one: the close path drops the link-list reference, and once
iso_conn_ready() drops its own reference at the end of the function the
socket is freed. The child socket, however, is already linked to the
freed parent, and a later disconnect of the child runs iso_chan_del()
-> bt_accept_unlink(), which dereferences the dangling parent pointer
into the freed accept queue (a use-after-free). The same dangling
pointer is also dereferenced through parent->***() in
iso_chan_del().
Fix it the same way the connected (non-BIS) path was fixed in commit
0d255e6 ("Bluetooth: ISO: hold sk properly in iso_conn_ready"):
after taking the socket lock, re-check that the parent is still a
listening, alive socket, and bail out otherwise.
Fixes: ccf74f2 ("Bluetooth: Add BTPROTO_ISO socket type")
Cc: [email protected]
Signed-off-by: Hang Nan <[email protected]>
Signed-off-by: Luiz Augusto von Dentz <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
net/bluetooth/iso.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=2387cd06a2c0b416f05028b02bba1089f54c28d9
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80914 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80914
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:H
The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
The Best / paranoid CVSS score: 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: 5
Paranoid ActionableScore: 6
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.
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need to tune this AI tool to make it better for this one and next similar).
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