CVE-2026-63980

Description

In the Linux kernel, the following vulnerability has been resolved: net/handshake: Use spin_lock_bh for hn_lock nvmet_tcp_state_change(), a socket callback that runs in BH context, can reach handshake_req_cancel() via nvmet_tcp_schedule_release_queue() and tls_handshake_cancel(). handshake_req_cancel() acquires hn->hn_lock with plain spin_lock(). If a process-context thread on the same CPU holds hn->hn_lock when a softirq invokes the cancel path, the lock attempt deadlocks. This is the only caller that invokes tls_handshake_cancel() from BH context; every other consumer calls it from process context. Deferring the cancel to process context in the NVMe target is not straightforward: nvmet_tcp_schedule_release_queue() must call tls_handshake_cancel() atomically with its state transition to DISCONNECTING. If the cancel were deferred, the handshake completion callback could fire in the window before the cancel runs, observe the unexpected state, and return without dropping its kref on the queue. Reworking that interlock is considerably more invasive than hardening the handshake lock. Convert all hn->hn_lock acquisitions from spin_lock/spin_unlock to spin_lock_bh/spin_unlock_bh so the lock is never taken with softirqs enabled.

Status

Show unmaintained releases

Package	Ubuntu Release	Status

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details

Severity score breakdown

CVSS version: CVSS v3.0

Base score 7.5 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	High

Scores

Parameter	Value
Base score	7.5 · High
Exploitability score	-
Impact score	-

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

References

Related Ubuntu Security Notices (USN)

USN-8593-1
Linux kernel vulnerabilities
23 July 2026

USN-8603-1
Linux kernel (Azure) vulnerabilities
24 July 2026

USN-8618-1
Linux kernel vulnerabilities
28 July 2026

USN-8663-1
Linux kernel (NVIDIA) vulnerabilities
20 August 2026

USN-8664-1
Linux kernel (NVIDIA BaseOS) vulnerabilities
20 August 2026

USN-8728-1
Linux kernel (GCP) vulnerabilities
7 September 2026

USN-8781-1
Linux kernel (NVIDIA Tegra) vulnerabilities
18 September 2026

USN-8728-2
Linux kernel (Azure) vulnerabilities
22 September 2026

USN-8728-3
Linux kernel (Oracle) vulnerabilities
29 September 2026

USN-8903-1
Linux kernel vulnerabilities
8 October 2026

USN-8906-1
Linux kernel (IBM) vulnerabilities
8 October 2026

USN-8905-1
Linux kernel (GCP) vulnerabilities
8 October 2026

USN-8904-1
Linux kernel (Azure) vulnerabilities
8 October 2026

USN-8903-2
Linux kernel vulnerabilities
9 October 2026

USN-8905-2
Linux kernel (GCP) vulnerabilities
9 October 2026