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CVE-2026-68189NVD status: Received

Linux: Concurrent Execution using Shared Resource with Improper Synchronization

Published Updated By the CyberSecBulletin desk

CVE-2026-68189 is a high-severity concurrent execution using shared resource with improper synchronization vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 30bc6248f035a792d1b1f4cc761b32fd5827b55f, e4fa2c5c261d736b8e58759fdef3a968d510630c, a351f68fb24828b23a971e00b8238ee0e8a40380 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.12% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 30bc6248f035a792d1b1f4cc761b32fd5827b55f or e4fa2c5c261d736b8e58759fdef3a968d510630c or a351f68fb24828b23a971e00b8238ee0e8a40380 or a42f5536ea9c00e13f0c0fbb330feed95e2365ca, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux161510ccf91c961638940b03abb1ee804be53a97 up to, but not including, 30bc6248f035a792d1b1f4cc761b32fd5827b55f; 161510ccf91c961638940b03abb1ee804be53a97 up to, but not including, e4fa2c5c261d736b8e58759fdef3a968d510630c; 161510ccf91c961638940b03abb1ee804be53a97 up to, but not including, a351f68fb24828b23a971e00b8238ee0e8a40380; 161510ccf91c961638940b03abb1ee804be53a97 up to, but not including, a42f5536ea9c00e13f0c0fbb330feed95e2365ca; 161510ccf91c961638940b03abb1ee804be53a97 up to, but not including, fe13adc258df88d95789e5673c7ba5178b5f8b28; 161510ccf91c961638940b03abb1ee804be53a97 up to, but not including, e9027ffbf5a0f3c12ca8900822e884eae9f0821b; 5.1730bc6248f035a792d1b1f4cc761b32fd5827b55f, e4fa2c5c261d736b8e58759fdef3a968d510630c, a351f68fb24828b23a971e00b8238ee0e8a40380, a42f5536ea9c00e13f0c0fbb330feed95e2365ca, fe13adc258df88d95789e5673c7ba5178b5f8b28, e9027ffbf5a0f3c12ca8900822e884eae9f0821b

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

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

Official description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: Protect UUID list traversal The hci_sync conversion moved class-of-device and EIR generation from an HCI request built under hdev->lock to asynchronous command sync work. The worker holds hdev->req_lock, but that lock does not serialize access to hdev->uuids against add_uuid() and remove_uuid(), which update the list under hdev->lock. The following interleaving can therefore occur: CPU0 (command sync work) CPU1 (management socket) fetch uuid from the list list_del(&uuid->list) kfree(uuid) read uuid->size KASAN reports the resulting use-after-free: BUG: KASAN: slab-use-after-free in eir_create+0xb8f/0xee0 Read of size 1 at addr ffff88810dbd8620 by task kworker/u17:0/87 Workqueue: hci0 hci_cmd_sync_work Call Trace: eir_create+0xb8f/0xee0 hci_update_eir_sync+0x1c0/0x330 hci_cmd_sync_work+0x13c/0x290 process_one_work+0x63a/0x1070 worker_thread+0x45b/0xd10 Allocated by task 86: __kasan_kmalloc+0x8f/0xa0 add_uuid+0x18a/0x4b0 hci_sock_sendmsg+0x1033/0x1ea0 Freed by task 92: __kasan_slab_free+0x43/0x70 kfree+0x131/0x3c0 remove_uuid+0x25e/0x560 hci_sock_sendmsg+0x1033/0x1ea0 Hold hdev->lock while generating and committing the class-of-device and EIR snapshots. Release it before sending an HCI command, so controller waits do not happen under the device lock. This protects all UUID list walks in these paths and restores the serialization lost in the command sync conversion.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Concurrent Execution using Shared Resource with Improper Synchronization

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

How developers prevent this class of flaw

  • In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
  • Use thread-safe capabilities such as the data access abstraction in Spring.
  • Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring. Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

More Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities (CWE-362)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities

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