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Linux Kernel EUVDEUVD-2026-55579

| CVE-2026-68393 HIGH
2026-08-10 Linux GHSA-mrp3-x3ff-8xj3
Information Disclosure Linux
8.8
CVSS 3.1 · Vendor: Linux
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Severity by source

Vendor (Linux) PRIMARY
8.8 HIGH
AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
7.5 HIGH

AV:A for Bluetooth proximity requirement; AC:H because winning the race condition between conn_hash lookup and concurrent deletion requires timing precision.

3.1 AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
4.0 AV:A/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
5.3 HIGH
AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Red Hat
7.0 MEDIUM
qualitative

Primary rating from Vendor (Linux).

CVSS VectorVendor: Linux

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

5
Analysis Generated
Aug 14, 2026 - 02:48 vuln.today
CVSS changed
Aug 13, 2026 - 23:37 NVD
8.8 (HIGH)
Patch available
Aug 10, 2026 - 14:18 EUVD
CVE Published
Aug 10, 2026 - 12:04 cve.org
HIGH 8.8
CVE Published
Aug 10, 2026 - 12:04 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

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

Bluetooth: hci_sync: extend conn_hash lookup critical sections

Using RCU-protected pointers outside the critical sections without refcount is incorrect and may result to UAF.

Extend critical section to cover both hci_conn_hash lookup and use of the returned conn.

Add surrounding rcu_read_lock() also when return value is not used, in preparation for RCU lockdep requirement to hci_lookup_le_connect().

This avoids concurrent deletion of the conn before we are done dereferencing it.

Also, make sure to hold hdev->lock when accessing hdev->accept_list.

AnalysisAI

Use-after-free in the Linux kernel Bluetooth HCI synchronization layer (hci_sync) allows adjacent, unauthenticated attackers to corrupt kernel memory, potentially achieving full system compromise. The root cause is that RCU-protected conn_hash lookup results were dereferenced outside RCU critical sections without holding a reference count, permitting concurrent deletion to free the connection object while it is still in use. With a CVSS score of 8.8 (AV:A), exploitation requires only Bluetooth adjacency and no privileges; however, the EPSS score of 0.17% (6th percentile) and absence from CISA KEV indicate no confirmed active exploitation or public weaponized exploit at time of analysis.

Technical ContextAI

The Linux kernel Bluetooth stack uses HCI (Host Controller Interface) as the primary interface between higher-level protocols (L2CAP, RFCOMM) and Bluetooth hardware. Connection state is tracked in a per-adapter conn_hash table protected by RCU (Read-Copy-Update), a lock-free synchronization mechanism that allows concurrent reads but requires careful discipline: pointers retrieved via rcu_dereference() are only valid within an rcu_read_lock() / rcu_read_unlock() critical section, or when a reference count is held. The vulnerability arises in hci_sync.c where hci_conn_hash_lookup_*() results were used after the critical section ended, creating a window where concurrent kfree() of the conn object (on connection teardown) could race with the dereferencing code, producing a classic CWE-416 Use-After-Free. Additionally, hdev->accept_list was accessed without holding hdev->lock, compounding the race surface. Affected CPE: cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:*.

RemediationAI

The primary fix is to upgrade to a patched Linux kernel version: 6.12.28 or later for 6.12.x users, 6.14.6 or later for 6.14.x users, 6.15.x with stable fix applied, 7.1.6 or later for 7.1.x users, or 7.2-rc4 or later for pre-release users. Stable fix commits are available directly at https://git.kernel.org/stable/c/83b7e67698d0b93f685875ce82c8d335436834f7, https://git.kernel.org/stable/c/38326774df6198df0cc2744cc73bf77cb741c538, and https://git.kernel.org/stable/c/d5efd6e4b8b0634af6843178fe1a7dd2b2178a3d. For systems where patching is not immediately feasible, the most effective compensating control is to disable Bluetooth entirely (rfkill block bluetooth or blacklist btusb/bluetooth kernel modules), which removes the attack surface completely but eliminates all Bluetooth functionality. Alternatively, restricting Bluetooth discoverability and disabling automatic pairing acceptance reduces the attack window but does not eliminate it, as unauthenticated connection initiation may still be possible depending on Bluetooth profile configuration. Distribution-specific packages (RHEL, Debian, Ubuntu) will carry these stable kernel backports - check your distribution's security advisories for availability.

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 16.0 Affected

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EUVD-2026-55579 vulnerability details – vuln.today
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