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CVE Record

CVE-2026-43023: Bluetooth: SCO: fix race conditions in sco_sock_connect()

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: SCO: fix race conditions in sco_sock_connect() sco_sock_connect() checks sk_state and sk_type without holding the socket lock. Two concurrent connect() syscalls on the same socket can both pass the check and enter sco_connect(), leading to use-after-free. The buggy scenario involves three participants and was confirmed with additional logging instrumentation: Thread A (connect): HCI disconnect: Thread B (connect): sco_sock_connect(sk) sco_sock_connect(sk) sk_state==BT_OPEN sk_state==BT_OPEN (pass, no lock) (pass, no lock) sco_connect(sk): sco_connect(sk): hci_dev_lock hci_dev_lock hci_connect_sco <- blocked -> hcon1 sco_conn_add->conn1 lock_sock(sk) sco_chan_add: conn1->sk = sk sk->conn = conn1 sk_state=BT_CONNECT release_sock hci_dev_unlock hci_dev_lock sco_conn_del: lock_sock(sk) sco_chan_del: sk->conn=NULL conn1->sk=NULL sk_state= BT_CLOSED SOCK_ZAPPED release_sock hci_dev_unlock (unblocked) hci_connect_sco -> hcon2 sco_conn_add -> conn2 lock_sock(sk) sco_chan_add: sk->conn=conn2 sk_state= BT_CONNECT // zombie sk! release_sock hci_dev_unlock Thread B revives a BT_CLOSED + SOCK_ZAPPED socket back to BT_CONNECT. Subsequent cleanup triggers double sock_put() and use-after-free. Meanwhile conn1 is leaked as it was orphaned when sco_conn_del() cleared the association. Fix this by: - Moving lock_sock() before the sk_state/sk_type checks in sco_sock_connect() to serialize concurrent connect attempts - Fixing the sk_type != SOCK_SEQPACKET check to actually return the error instead of just assigning it - Adding a state re-check in sco_connect() after lock_sock() to catch state changes during the window between the locks - Adding sco_pi(sk)->conn check in sco_chan_add() to prevent double-attach of a socket to multiple connections - Adding hci_conn_drop() on sco_chan_add failure to prevent HCI connection leaks

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A race in the Linux Bluetooth SCO socket code can corrupt kernel memory when concurrent local connection attempts overlap with a disconnect. A low-privileged local process may trigger use-after-free, potentially compromising confidentiality, integrity, or availability. The supplied record rates it CVSS 7.8 (High).

Executive priority

Prioritize patching shared Linux systems, endpoints running untrusted applications, and Bluetooth-enabled devices. The issue has high potential impact but requires local access; therefore, internet-facing status alone does not increase exposure. Use vendor package guidance before declaring systems vulnerable or remediated.

Technical view

sco_sock_connect() checked socket state and type without holding the socket lock. Concurrent connect() calls plus HCI disconnection could revive a closed socket, double-release references, leak a connection, and cause use-after-free. The fix serializes checks, revalidates state, prevents double attachment, returns type errors, and drops failed HCI connections.

Likely exposure

Exposure is limited to affected Linux kernels where a local low-privileged process can reach Bluetooth SCO socket functionality. The record identifies multiple affected versions, but its version data is difficult to interpret without distribution-specific mapping. Remote exploitation by a Bluetooth peer alone is not established by the supplied evidence.

Exploitation context

The CVSS vector indicates a local, low-complexity, low-privilege attack requiring no user interaction. Successful triggering depends on concurrent operations and disconnect timing. The CVE is not listed as KEV, and the supplied sources provide no evidence of active exploitation or a public exploit.

Researcher notes

The documented failure requires two connect attempts on the same SCO socket overlapping with HCI teardown. Observable consequences include a zombie socket, double sock_put(), use-after-free, and an orphaned connection. The sources document corrective commits but do not establish reliable exploitation, practical privilege escalation, or affected distribution package versions.

Mitigation direction

  • Update to a vendor-supported kernel containing the applicable stable fix or backport.
  • Consult the Linux distribution's advisory to map packaged kernel versions to the cited fixes.
  • Restrict untrusted local access while affected systems await updates.
  • Where operationally acceptable, reduce exposure to unused Bluetooth functionality pending remediation.

Validation and detection

  • Inventory running kernel versions on systems that provide Bluetooth functionality.
  • Map distribution kernel builds to the affected ranges and cited stable commits.
  • Confirm the applicable fix is present after updating, including vendor backports.
  • Review kernel logs for Bluetooth SCO faults, use-after-free reports, or unexpected crashes.
Prepared
Confidence
medium
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2026-43023 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
7Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-43023Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux70a13b1e25fef37c87c8a1228ddb8900efbca7cf, 9a8ec9e8ebb5a7c0cfbce2d6b4a6b67b2b78e8f3, 9a8ec9e8ebb5a7c0cfbce2d6b4a6b67b2b78e8f3, 9a8ec9e8ebb5a7c0cfbce2d6b4a6b67b2b78e8f3, 9a8ec9e8ebb5a7c0cfbce2d6b4a6b67b2b78e8f3, 9a8ec9e8ebb5a7c0cfbce2d6b4a6b67b2b78e8f3, 6.1.109unaffected
LinuxLinux6.3, 0, 6.1.168, 6.6.134, 6.12.81, 6.18.22, 6.19.12, 7.0affected
Weakness

CWE details

No CWE listed

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