CVE-2026-53357 - Vulnerability Details

- Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del()

Description

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

Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del()

bt_accept_dequeue() unlinks a not-yet-accepted child from the parent
accept queue and release_sock()s it before returning, so the returned
sk has no caller reference and is unlocked.

l2cap_sock_cleanup_listen() walks these children on listening-socket
close. A concurrent HCI disconnect drives hci_rx_work ->
l2cap_conn_del() which runs l2cap_chan_del() + l2cap_sock_kill() and
frees the child sk and its l2cap_chan; cleanup_listen() then uses both:

BUG: KASAN: slab-use-after-free in l2cap_sock_kill
l2cap_sock_kill / l2cap_sock_cleanup_listen / __x64_sys_close
Freed by: l2cap_conn_del -> l2cap_sock_close_cb -> l2cap_sock_kill

This is distinct from the two fixes already in this area: commit
e83f5e24da741 ("Bluetooth: serialize accept_q access") serialises the
accept_q list/poll and takes temporary refs inside bt_accept_dequeue(),
and CVE-2025-39860 serialises the userspace close()/accept() race by
calling cleanup_listen() under lock_sock() in l2cap_sock_release().
Neither covers l2cap_conn_del() running from hci_rx_work, so this UAF
still reproduces on current bluetooth/master.

Take the reference at the source: bt_accept_dequeue() does sock_hold()
while sk is still locked, before release_sock(); callers sock_put().
cleanup_listen() pins the chan with l2cap_chan_hold_unless_zero() under
a brief child sk lock (serialising vs l2cap_sock_teardown_cb()), drops
it before l2cap_chan_lock(), and skips a duplicate l2cap_sock_kill() on
SOCK_DEAD. conn->lock is not taken here: cleanup_listen() runs under
the parent sk lock and that would invert
conn->lock -> chan->lock -> sk_lock (lockdep).

KASAN/SMP: an unprivileged listen/close vs HCI-disconnect race produced
12 use-after-free reports per run before this change; 0, and no lockdep
report, over 1600+ raced iterations after it on bluetooth/master.

Published: 2026-07-02

Score: 8 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The flaw is a use‑after‑free (CWE‑416) in the Linux kernel’s Bluetooth L2CAP module. When a user space process closes a listening socket while the kernel simultaneously processes a HCI disconnect, the cleanup routine accesses a socket structure that has already been freed. This misuse can trigger a kernel panic, resulting in a system crash. The CVE description does not state that the flaw leads to privilege escalation, only that it produces a crash report and that it was tracked as a race condition. It also constitutes a race condition (CWE‑366).

Affected Systems

Any Linux kernel build that includes the Bluetooth L2CAP implementation and has not received the recent patch is potentially affected. This includes all distribution kernels that compile the default Bluetooth stack, regardless of version. The vulnerability is relevant to servers, desktops, embedded devices, and networking equipment that enable Bluetooth.

Risk and Exploitability

The CVSS score of 8 indicates a high‑severity issue; however, the EPSS score is below 1%, suggesting a very low probability of widespread exploitation at this time. The issue is not listed in the CISA KEV catalog. The race condition would require an attacker to induce simultaneous userspace socket close and HCI disconnect events. The description does not explicitly state the attack vector, but it is inferred that a local or remote attacker could trigger the race over the Bluetooth interface. Successful exploitation would most likely cause a kernel crash, leading to denial of service, although the description does not confirm if arbitrary code execution is possible.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`15f02b91056253e8cdc592888f431da0731337b8`	affected	< 751de6ec671fe75ad9cf65a0638d2a06b6a5984d
`15f02b91056253e8cdc592888f431da0731337b8`	affected	< 407217734835d21d4e0105ebf347860dc1806f88
`15f02b91056253e8cdc592888f431da0731337b8`	affected	< 7eebd4c2c86f573af87ff165d08a83432eb0b919
`15f02b91056253e8cdc592888f431da0731337b8`	affected	< 5d86d2f1b4d9a508c441d3e45277ae1a73cfed57
`15f02b91056253e8cdc592888f431da0731337b8`	affected	< 87c543e2f78d0871f271df92dab98901bbd5b6f5
`15f02b91056253e8cdc592888f431da0731337b8`	affected	< added1213395071470a900cc845a042fb51882a6
`15f02b91056253e8cdc592888f431da0731337b8`	affected	< a5ca86a6097a8b030ca3226cd300b17ed330f966
`15f02b91056253e8cdc592888f431da0731337b8`	affected	< ab1513597c6cf17cd1ad2a21e3b045421b48e022

Linux

affected

Version	Status	Constraints
`5.7`	affected	—
`0`	unaffected	< 5.7
`5.10.259`	unaffected	≤ 5.10.*
`5.15.210`	unaffected	≤ 5.15.*
`6.1.175`	unaffected	≤ 6.1.*
`6.6.142`	unaffected	≤ 6.6.*
`6.12.92`	unaffected	≤ 6.12.*
`6.18.34`	unaffected	≤ 6.18.*
`7.0.11`	unaffected	≤ 7.0.*
`7.1`	unaffected	≤ *

Configuration 1 [-]

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel:7.1:rc1::::::
	cpe:2.3:o:linux:linux_kernel:7.1:rc2::::::
	cpe:2.3:o:linux:linux_kernel:7.1:rc3::::::
	cpe:2.3:o:linux:linux_kernel:7.1:rc4::::::

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[15f02b91056253e8cdc592888f431da0731337b8,751de6ec671fe75ad9cf65a0638d2a06b6a5984d)`	affected	code_commit	—
`[15f02b91056253e8cdc592888f431da0731337b8,407217734835d21d4e0105ebf347860dc1806f88)`	affected	code_commit	—
`[15f02b91056253e8cdc592888f431da0731337b8,7eebd4c2c86f573af87ff165d08a83432eb0b919)`	affected	code_commit	—
`[15f02b91056253e8cdc592888f431da0731337b8,5d86d2f1b4d9a508c441d3e45277ae1a73cfed57)`	affected	code_commit	—
`[15f02b91056253e8cdc592888f431da0731337b8,87c543e2f78d0871f271df92dab98901bbd5b6f5)`	affected	code_commit	—
`[15f02b91056253e8cdc592888f431da0731337b8,added1213395071470a900cc845a042fb51882a6)`	affected	code_commit	—
`[15f02b91056253e8cdc592888f431da0731337b8,a5ca86a6097a8b030ca3226cd300b17ed330f966)`	affected	code_commit	—
`[15f02b91056253e8cdc592888f431da0731337b8,ab1513597c6cf17cd1ad2a21e3b045421b48e022)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`5.7`	affected	generic	—
`[0,5.7)`	unaffected	generic	—
`[5.10.259,5.11.0)`	unaffected	semver	—
`[5.15.210,5.16.0)`	unaffected	semver	—
`[6.1.175,6.2.0)`	unaffected	semver	—
`[6.6.142,6.7.0)`	unaffected	semver	—
`[6.12.92,6.13.0)`	unaffected	semver	—
`[7.0.11,7.1.0)`	unaffected	semver	—
`[7.1,*]`	unaffected	generic	—

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Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Upgrade the Linux kernel to a version containing the l2cap use‑after‑free fix referenced in the advisory
If Bluetooth functionality is not required, unload the Bluetooth kernel module and stop associated services
Configure access controls (e.g., SELinux or AppArmor) to restrict which processes can create or close L2CAP sockets

Generated by OpenCVE AI on August 12, 2026 at 09:42 UTC.

Tracking

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Advisories

Source	ID	Title
Debian DLA	DLA-4664-1	linux security update
Debian DLA	DLA-4665-1	linux security update
Debian DLA	DLA-4671-1	linux-6.1 security update
Ubuntu USN	USN-8566-1	Linux kernel vulnerabilities
Ubuntu USN	USN-8568-1	Linux kernel (OEM) vulnerabilities
Ubuntu USN	USN-8569-1	Linux kernel (HWE) vulnerabilities
Ubuntu USN	USN-8593-1	Linux kernel vulnerabilities
Ubuntu USN	USN-8603-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-8618-1	Linux kernel vulnerabilities

No CVSS v4.0

Attack Vector Adjacent Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00258.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/407217734835d21d4e0105ebf347860dc1806f88
https://git.kernel.org/stable/c/5d86d2f1b4d9a508c441d3e45277ae1a73cfed57
https://git.kernel.org/stable/c/751de6ec671fe75ad9cf65a0638d2a06b6a5984d
https://git.kernel.org/stable/c/7eebd4c2c86f573af87ff165d08a83432eb0b919
https://git.kernel.org/stable/c/87c543e2f78d0871f271df92dab98901bbd5b6f5
https://git.kernel.org/stable/c/a5ca86a6097a8b030ca3226cd300b17ed330f966
https://git.kernel.org/stable/c/ab1513597c6cf17cd1ad2a21e3b045421b48e022
https://git.kernel.org/stable/c/added1213395071470a900cc845a042fb51882a6
https://lore.kernel.org/linux-cve-announce/2026070234-CVE-2026-53357-18f1@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-53357
https://www.cve.org/CVERecord?id=CVE-2026-53357

History

Sat, 18 Jul 2026 08:00:00 +0000

Type	Values Removed	Values Added
Metrics	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}`	cvssV3_1 `{'score': 8, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}`

Fri, 03 Jul 2026 00:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-366
References		https://lore.kernel.org/linux-cve-announce/2026070234-CVE-2026-53357-18f1@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-53357 https://www.cve.org/CVERecord?id=CVE-2026-53357
Metrics	threat_severity `None`	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}` threat_severity `Moderate`

Thu, 02 Jul 2026 14:30:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del() bt_accept_dequeue() unlinks a not-yet-accepted child from the parent accept queue and release_sock()s it before returning, so the returned sk has no caller reference and is unlocked. l2cap_sock_cleanup_listen() walks these children on listening-socket close. A concurrent HCI disconnect drives hci_rx_work -> l2cap_conn_del() which runs l2cap_chan_del() + l2cap_sock_kill() and frees the child sk and its l2cap_chan; cleanup_listen() then uses both: BUG: KASAN: slab-use-after-free in l2cap_sock_kill l2cap_sock_kill / l2cap_sock_cleanup_listen / __x64_sys_close Freed by: l2cap_conn_del -> l2cap_sock_close_cb -> l2cap_sock_kill This is distinct from the two fixes already in this area: commit e83f5e24da741 ("Bluetooth: serialize accept_q access") serialises the accept_q list/poll and takes temporary refs inside bt_accept_dequeue(), and CVE-2025-39860 serialises the userspace close()/accept() race by calling cleanup_listen() under lock_sock() in l2cap_sock_release(). Neither covers l2cap_conn_del() running from hci_rx_work, so this UAF still reproduces on current bluetooth/master. Take the reference at the source: bt_accept_dequeue() does sock_hold() while sk is still locked, before release_sock(); callers sock_put(). cleanup_listen() pins the chan with l2cap_chan_hold_unless_zero() under a brief child sk lock (serialising vs l2cap_sock_teardown_cb()), drops it before l2cap_chan_lock(), and skips a duplicate l2cap_sock_kill() on SOCK_DEAD. conn->lock is not taken here: cleanup_listen() runs under the parent sk lock and that would invert conn->lock -> chan->lock -> sk_lock (lockdep). KASAN/SMP: an unprivileged listen/close vs HCI-disconnect race produced 12 use-after-free reports per run before this change; 0, and no lockdep report, over 1600+ raced iterations after it on bluetooth/master.
Title		Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del()
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/407217734835d21d4e0105ebf347860dc1806f88 https://git.kernel.org/stable/c/5d86d2f1b4d9a508c441d3e45277ae1a73cfed57 https://git.kernel.org/stable/c/751de6ec671fe75ad9cf65a0638d2a06b6a5984d https://git.kernel.org/stable/c/7eebd4c2c86f573af87ff165d08a83432eb0b919 https://git.kernel.org/stable/c/87c543e2f78d0871f271df92dab98901bbd5b6f5 https://git.kernel.org/stable/c/a5ca86a6097a8b030ca3226cd300b17ed330f966 https://git.kernel.org/stable/c/ab1513597c6cf17cd1ad2a21e3b045421b48e022 https://git.kernel.org/stable/c/added1213395071470a900cc845a042fb51882a6

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-07-02T13:43:17.077Z

Updated: 2026-08-05T12:35:06.665Z

Reserved: 2026-06-09T07:44:35.400Z

Link: CVE-2026-53357

Vulnrichment

No data.

NVD

Status : Analyzed

Published: 2026-07-02T15:17:03.103

Modified: 2026-07-22T19:06:30.080

Link: CVE-2026-53357

Redhat

Severity : Moderate

Publid Date: 2026-07-02T00:00:00Z

Links: CVE-2026-53357 - Bugzilla

OpenCVE Enrichment

Updated: 2026-08-12T09:45:01Z

Weaknesses

CWE-366
Race Condition within a Thread
CWE-416
Use After Free

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Adjacent Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Subscriptions

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