KEVWire

Security intelligence, with context.

Response snapshot Oct 27, 2026, 04:51 UTC

Back to the wire
Permalink
VulnerabilityCVE-2026-99011

Linux kernel: Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata()

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata() sco_recv_scodata() upgrades the weak hcon->sco_data back-pointer to a strong reference under hdev->lock: hci_dev_lock(hdev); hcon = hci_conn_hash_lookup_handle(hdev, handle); ...

At a glance

Exploited
Not known
Severity
7.1 High (CVSS 3.1)
Chance of exploitation
0.2% in the next 30 days
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-99011 (opens a new tab)

What happened

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata()

sco_recv_scodata() upgrades the weak hcon->sco_data back-pointer to a strong reference under hdev->lock:

hci_dev_lock(hdev); hcon = hci_conn_hash_lookup_handle(hdev, handle); ... conn = sco_conn_hold_unless_zero(hcon->sco_data); hci_dev_unlock(hdev);

Continue reading

but the pointer is cleared from the other side without that lock. When the last sco_conn reference is dropped, sco_conn_free() ran

conn->hcon->sco_data = NULL;

with no hdev->lock held, so the RX path could read hcon->sco_data and call kref_get_unless_zero() on an sco_conn that was concurrently freed:

BUG: KASAN: slab-use-after-free in sco_conn_hold_unless_zero+0xbe/0x160 Write of size 4 by task kworker/u17:0 Workqueue: hci0 hci_rx_work Call Trace: sco_conn_hold_unless_zero+0xbe/0x160 sco_recv_scodata+0x13f/0x490 hci_rx_work+0x3af/0x730

kref_get_unless_zero() only guards against a zero refcount, not against the backing memory already being freed.

Give hcon->sco_data an actual reference on the sco_conn it points to, so the object cannot be freed while the pointer is still installed, and only clear and drop it from sco_conn_del(), which runs under hdev->lock (its callers, sco_connect_cfm() and sco_disconn_cfm(), hold it).

The reader in sco_recv_scodata() also takes hdev->lock, so the store and the read are now serialised: the RX path either observes NULL or a reference that is guaranteed to stay valid until it drops its own.

sco_conn_add() no longer hands its kref_init() reference to the caller as the connection's only reference; that initial reference is the one owned by hcon->sco_data, and callers get their own via sco_conn_hold().

Because the sco_conn can now outlive the socket (the association keeps it alive until the link goes down), the hci_conn can no longer be dropped from sco_conn_free() without regressing socket close: closing a connected SCO socket must still tear the link down.

Move hci_conn ownership to the socket instead: __sco_chan_add() takes an hci_conn reference and it is released from sco_chan_del() and sco_sock_destruct(), exactly once. The sco_conn no longer owns an hci_conn reference, so sco_conn_add() stops consuming one and sco_connect() drops the hci_connect_sco() reference on every path; sco_connect_cfm() no longer needs its hci_conn_hold() dance.

Scores and how they were measured

CVSS base severity

7.1

Version 3.1As of

CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.2%

Scored Percentile 13.1%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-99011 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-99011, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 24). Linux kernel: Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata() (CVE-2026-99011). https://kevwire.com/record/CVE-2026-99011

MLA

"Linux kernel: Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata() (CVE-2026-99011)." KEVWire, 24 Oct. 2026, kevwire.com/record/CVE-2026-99011.

Chicago

KEVWire. "Linux kernel: Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata() (CVE-2026-99011)." Last modified October 24, 2026. https://kevwire.com/record/CVE-2026-99011.

Evidence summary (plain text)

Linux kernel: Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata() (Oct 23, 2026).
In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata()

sco_recv_scodata() upgrades the weak hcon->sco_data back-pointer to a
strong reference under hdev->lock:

    hci_dev_lock(hdev);
    hcon = hci_conn_hash_lookup_handle(hdev, handle);
    ...
    conn = sco_conn_hold_unless_zero(hcon->sco_data);
    hci_dev_unlock(hdev);

but the pointer is cleared from the other side without that lock. When
the last sco_conn reference is dropped, sco_conn_free() ran

    conn->hcon->sco_data = NULL;

with no hdev->lock held, so the RX path could read hcon->sco_data and
call kref_get_unless_zero() on an sco_conn that was concurrently freed:

    BUG: KASAN: slab-use-after-free in sco_conn_hold_unless_zero+0xbe/0x160
    Write of size 4 by task kworker/u17:0
    Workqueue: hci0 hci_rx_work
    Call Trace:
     sco_conn_hold_unless_zero+0xbe/0x160
     sco_recv_scodata+0x13f/0x490
     hci_rx_work+0x3af/0x730

kref_get_unless_zero() only guards against a zero refcount, not against
the backing memory already being freed.

Give hcon->sco_data an actual reference on the sco_conn it points to, so
the object cannot be freed while the pointer is still installed, and only
clear and drop it from sco_conn_del(), which runs under hdev->lock (its
callers, sco_connect_cfm() and sco_disconn_cfm(), hold it). The reader in
sco_recv_scodata() also takes hdev->lock, so the store and the read are
now serialised: the RX path either observes NULL or a reference that is
guaranteed to stay valid until it drops its own.

sco_conn_add() no longer hands its kref_init() reference to the caller as
the connection's only reference; that initial reference is the one owned
by hcon->sco_data, and callers get their own via sco_conn_hold().

Because the sco_conn can now outlive the socket (the association keeps it
alive until the link goes down), the hci_conn can no longer be dropped
from sco_conn_free() without regressing socket close: closing a connected
SCO socket must still tear the link down. Move hci_conn ownership to the
socket instead: __sco_chan_add() takes an hci_conn reference and it is
released from sco_chan_del()
CVSS 7.1 (version 3.1; evidence as of Oct 24, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-99011).
EPSS 0.2% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-99011&date=2026-10-26).
Sources:
NVD CVE-2026-99011: https://nvd.nist.gov/vuln/detail/CVE-2026-99011
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=9000
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-99011&date=2026-10-26
Record ID: CVE-2026-99011.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 01:40 UTC. Ingestion is not an independent editorial investigation.

NVD status: Received. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

Record JSON

Your account

Email alerts

Email alerts are not available yet. To follow your stack today, use its RSS feed, which honors your filters, or connect an AI agent through the API.

Suggest an improvement

Ideas, missing sources, corrections, and bugs are all welcome. No account needed. Suggestions are reviewed by a person before anything changes.

Record details

Record detail