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CVE Record

CVE-2023-54038: Bluetooth: hci_conn: return ERR_PTR instead of NULL when there is no link

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_conn: return ERR_PTR instead of NULL when there is no link hci_connect_sco currently returns NULL when there is no link (i.e. when hci_conn_link() returns NULL). sco_connect() expects an ERR_PTR in case of any error (see line 266 in sco.c). Thus, hcon set as NULL passes through to sco_conn_add(), which tries to get hcon->hdev, resulting in dereferencing a NULL pointer as reported by syzkaller. The same issue exists for iso_connect_cis() calling hci_connect_cis(). Thus, make hci_connect_sco() and hci_connect_cis() return ERR_PTR instead of NULL.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel Bluetooth flaw is a coding error where an expected error value can instead be NULL. In affected Bluetooth connection paths, that can lead to a NULL pointer dereference. Public sources provide no CVSS score, no KEV listing, and no cited evidence of active exploitation.

Executive priority

Treat this as a maintenance-priority kernel issue unless local exposure is high. Patch through normal Linux update channels, with higher urgency for systems using Bluetooth or exposed to untrusted local or proximity-based interaction.

Technical view

hci_connect_sco() and hci_connect_cis() returned NULL when no link existed, while callers expected ERR_PTR-style errors. That allowed NULL to reach sco_conn_add(), which dereferenced hcon->hdev. The issue was reported by syzkaller and resolved by returning ERR_PTR instead of NULL.

Likely exposure

Exposure is limited to Linux systems using affected kernel Bluetooth code paths. The supplied data identifies Linux kernel entries around 6.4 to 6.5 as affected, but version data is incomplete and commit-based. Downstream distribution backports must be checked.

Exploitation context

The bundle does not cite public exploit code, exploitation in the wild, or CISA KEV inclusion. The evidence supports a kernel Bluetooth NULL pointer dereference found by automated testing, not active exploitation.

Researcher notes

The core issue is error-handling contract mismatch between hci connection helpers and SCO/ISO callers. Source evidence names syzkaller, NULL propagation, and fixes in stable commits. No CVSS, CWE, exploitability analysis, or detailed affected matrix is provided.

Mitigation direction

  • Check Linux vendor or distribution advisories for CVE-2023-54038 coverage.
  • Update to a kernel package containing the referenced stable fixes.
  • If Bluetooth is unnecessary, disable or restrict Bluetooth services pending patching.
  • Prioritize systems where untrusted users or nearby devices can reach Bluetooth functionality.

Validation and detection

  • Inventory Linux kernel versions and downstream package patch levels.
  • Compare kernel source or changelog against the referenced stable commits.
  • Confirm Bluetooth is enabled only where operationally required.
  • Review kernel logs for Bluetooth-related crashes or NULL pointer faults.
Prepared
Confidence
medium
Sources
4

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-2023-54038 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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.

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

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
LinuxLinux06149746e7203d5ffe2d6faf9799ee36203aa8b8, 06149746e7203d5ffe2d6faf9799ee36203aa8b8, f72fc94a17d45be98aecfd59c39b5b24a6a342e2, 6.3.8unaffected
LinuxLinux6.4, 0, 6.4.7, 6.5affected
Weakness

CWE details

No CWE listed

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