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Vulnerabilities

Vulnerability · CVE-2026-90091

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs.

Published Sep 17, 2026 · catalog updated Oct 21, 2026 · In the Linux kernel,

Check if you run it

No confirmed exploitation is on record for CVE-2026-90091. EPSS is 0.35%. Act only if a listed version of In the Linux kernel, is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (In the Linux kernel,).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.35%
Remediation
Advisory link
Affected products
Ubuntu:16.04:LTS linux-hwe-edge · Ubuntu:18.04:LTS linux-aws-5.0 · Ubuntu:18.04:LTS linux-aws-5.3 · Ubuntu:18.04:LTS linux-azure · Ubuntu:18.04:LTS linux-azure-5.3 · Ubuntu:18.04:LTS linux-azure-edge

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan For L2CAP sockets without owning sk->sk_socket, reading l2cap_pi(sk)->chan may race against concurrent l2cap_sock_kill() -> l2cap_sock_put_chan(). This excludes simultaneous proto_ops callbacks, but access in l2cap_sock_cleanup_listen() has unsafe lockless read. [Task 1] [Task 2 (hdev->workqueue)] l2cap_sock_release(parent) l2cap_disconn_cfm l2cap_sock_cleanup_listen l2cap_conn_del bt_accept_dequeue l2cap_chan_del lock_sock(sk) l2cap_sock_teardown_cb bt_accept_unlink bt_sk(sk)->parent = NULL release_sock(sk) ----------------> lock_sock(sk) parent = /* NULL */ lock_sock(sk) chan l2cap_pi(sk)->chan = NULL l2cap_chan_hold_unless_zero l2cap_put_chan(chan) kref_get_unless_zero(&chan->ref) Task 1 may observe NULL which causes null-ptr-deref. Fix the race by taking lock_sock() in l2cap_sock_kill() to synchronize with l2cap_sock_cleanup_listen(). hold_unless_zero() is not needed here, l2cap_pi(sk)->chan owns reference if it is non-NULL. Clarify code comments vs. locking.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Ubuntu:16.04:LTS linux-hwe-edge4.8.0-28.30~16.04.1, 4.8.0-30.32~16.04.1, 4.8.0-32.34~16.04.1
  • Ubuntu:18.04:LTS linux-aws-5.05.0.0-1021.24~18.04.1, 5.0.0-1022.25~18.04.1, 5.0.0-1023.26~18.04.1
  • Ubuntu:18.04:LTS linux-aws-5.35.3.0-1016.17~18.04.1, 5.3.0-1017.18~18.04.1, 5.3.0-1019.21~18.04.1
  • Ubuntu:18.04:LTS linux-azure4.15.0-1002.2, 4.15.0-1003.3, 4.15.0-1004.4
  • Ubuntu:18.04:LTS linux-azure-5.35.3.0-1007.8~18.04.1, 5.3.0-1008.9~18.04.1, 5.3.0-1009.10~18.04.1
  • Ubuntu:18.04:LTS linux-azure-edge4.18.0-1006.6~18.04.1, 4.18.0-1007.7~18.04.1, 4.18.0-1008.8~18.04.1
  • Ubuntu:18.04:LTS linux-gcp4.15.0-1001.1, 4.15.0-1003.3, 4.15.0-1005.5
  • Ubuntu:18.04:LTS linux-gcp-5.35.3.0-1008.9~18.04.1, 5.3.0-1009.10~18.04.1, 5.3.0-1010.11~18.04.1
  • Ubuntu:18.04:LTS linux-gke-4.154.15.0-1030.32, 4.15.0-1032.34, 4.15.0-1033.35
  • Ubuntu:18.04:LTS linux-gke-5.45.4.0-1025.25~18.04.1, 5.4.0-1027.28~18.04.1, 5.4.0-1029.31~18.04.1
  • Ubuntu:18.04:LTS linux-gkeop-5.45.4.0-1001.1, 5.4.0-1003.3, 5.4.0-1004.5
  • Ubuntu:18.04:LTS linux-hwe4.18.0-13.14~18.04.1, 4.18.0-14.15~18.04.1, 4.18.0-15.16~18.04.1

How to fix CVE-2026-90091

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-90091. EPSS is 0.35%. Act only if a listed version of In the Linux kernel, is installed.

Which versions are affected?

Compare what you have installed with 4.8.0-28.30~16.04.1, 4.8.0-30.32~16.04.1, 4.8.0-32.34~16.04.1, 5.0.0-1021.24~18.04.1, 5.0.0-1022.25~18.04.1, 5.0.0-1023.26~18.04.1, 5.3.0-1016.17~18.04.1, 5.3.0-1017.18~18.04.1, 5.3.0-1019.21~18.04.1, 4.15.0-1002.2, 4.15.0-1003.3, 4.15.0-1004.4, 5.3.0-1007.8~18.04.1, 5.3.0-1008.9~18.04.1, 5.3.0-1009.10~18.04.1, 4.18.0-1006.6~18.04.1, 4.18.0-1007.7~18.04.1, 4.18.0-1008.8~18.04.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.35%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Ubuntu security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 17, 2026 · OpenSSF OSV / OSV Scanner

    Detected

    In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan For L2CAP sockets without owning sk->sk_socket, reading l2cap_pi(sk)->chan may race against concurrent l2cap_sock_kill() -> l2cap_sock_put_chan(). This excludes simultaneous proto_ops callbacks, but access in l2cap_sock_cleanup_listen() has unsafe lockless read. [

  2. Oct 21, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan For L2CAP sockets without owning sk->sk_socket, reading l2cap_pi(sk)->chan may race against concurrent l2cap_sock_kill() -> l2cap_sock_put_chan(). This excludes simultaneous proto_ops callbacks, but access in l2cap_sock_cleanup_listen() has unsafe lockless read. [

Sources

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.