Bug 2536720 (CVE-2026-90256)

Summary:	CVE-2026-90256 kernel: Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's Bluetooth L2CAP (Logical Link Control and Adaptation Protocol) component. A use-after-free (UAF) vulnerability can occur when `hci_conn::l2cap_data` is accessed without proper locking during the disconnection indication process. This can lead to a system crash or potentially allow an attacker to execute arbitrary code.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-17 19:19:11 UTC

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

Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind

hci_conn::l2cap_data is accessed without locks in l2cap_disconn_ind via
hci_conn_timeout (disc_work) -> hci_proto_disconn_ind ->
l2cap_disconn_ind.  This is UAF if the l2cap_conn is deleted
concurrently.

disc_work is disabled sync in hci_conn_del(), so we cannot take
hci_dev_lock in disc_work.

Fix by using proto_lock to guard l2cap_data, in addition to hdev->lock
which is held in other access paths.

Comment 1 gkamathe 2026-09-23 20:40:10 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90256.mbox