CVE-2026-64340 - Vulnerability Details

- USB: legousbtower: fix use-after-free on disconnect race

Description

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

USB: legousbtower: fix use-after-free on disconnect race

mutex_unlock() may access the mutex structure after releasing the lock
and therefore cannot be used to manage lifetime of objects directly
(unlike spinlocks and refcounts). [1][2]

Use a kref to release the driver data to avoid use-after-free in
mutex_unlock() when release() races with disconnect().

[1] a51749ab34d9 ("locking/mutex: Document that mutex_unlock() is
non-atomic")
[2] 2b9d9e0a9ba0 ("locking/mutex: Clarify that mutex_unlock(), and most
other sleeping locks, can still use the lock object
after it's unlocked")

Published: 2026-07-25

Score: 7.0 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

A race condition between the legacy USB tower driver’s release routine and its disconnect path allows a mutex unlock operation to access a freed driver data structure. The resulting use-after-free can corrupt kernel memory during a USB unplug/replug cycle, potentially compromising kernel integrity.

Affected Systems

The flaw resides in the Linux kernel’s legacy USB handler. Any kernel version that deploys the legacy USB driver before the referenced commits (0b57e5dd, 11d069f858, 62fc8eb1, 6462de75d2e, 766738ecf, 9ba629664, ab2bfd7bec, or b4222c05066b) is potentially vulnerable. Kernel builds without the legacy USB subsystem, or with the driver disabled, remain unexposed.

Risk and Exploitability

The EPSS score is reported as < 1%, indicating a low probability of widespread exploitation. The vulnerability is not listed in the CISA KEV catalog. Exploitation requires local control over USB plug/unplug events to trigger the race; a remote attacker cannot directly exploit the flaw. The likely attack vector is local, as it appears to depend on the ability to manipulate USB hardware on the host, but this is inferred from the description.

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
`18bcbcfe9ca2308ebffb40068b51803da9315d97`	affected	< 11d069f85851997b4ea0adf242ed9672dc749b8f
`18bcbcfe9ca2308ebffb40068b51803da9315d97`	affected	< b4222c05066b252b451f9c8c4730b5b60824ea66
`18bcbcfe9ca2308ebffb40068b51803da9315d97`	affected	< 6462de75d2e370c7e74dcfb7b4ae79eb5a6a55ee
`18bcbcfe9ca2308ebffb40068b51803da9315d97`	affected	< 0b57e5ddbd89df3bc367463de3d2ca66f99a1a5e
`18bcbcfe9ca2308ebffb40068b51803da9315d97`	affected	< ab2bfd7bec4f134b377ec42f513e90c35db94160
`18bcbcfe9ca2308ebffb40068b51803da9315d97`	affected	< 766738ecf2b819e54d38763c8d1c8ae6cff14b39
`18bcbcfe9ca2308ebffb40068b51803da9315d97`	affected	< 9ba62966461a8e3cc593b62c56ec62eb2d80436d
`18bcbcfe9ca2308ebffb40068b51803da9315d97`	affected	< 62fc8eb1b1481051f7bab4aa93d79809053dd09f

Linux

affected

Version	Status	Constraints
`2.6.25`	affected	—
`0`	unaffected	< 2.6.25
`5.10.261`	unaffected	≤ 5.10.*
`5.15.212`	unaffected	≤ 5.15.*
`6.1.178`	unaffected	≤ 6.1.*
`6.6.145`	unaffected	≤ 6.6.*
`6.12.96`	unaffected	≤ 6.12.*
`6.18.39`	unaffected	≤ 6.18.*
`7.1.4`	unaffected	≤ 7.1.*
`7.2-rc3`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[18bcbcfe9ca2308ebffb40068b51803da9315d97,11d069f85851997b4ea0adf242ed9672dc749b8f)`	affected	code_commit	—
`[18bcbcfe9ca2308ebffb40068b51803da9315d97,b4222c05066b252b451f9c8c4730b5b60824ea66)`	affected	code_commit	—
`[18bcbcfe9ca2308ebffb40068b51803da9315d97,6462de75d2e370c7e74dcfb7b4ae79eb5a6a55ee)`	affected	code_commit	—
`[18bcbcfe9ca2308ebffb40068b51803da9315d97,0b57e5ddbd89df3bc367463de3d2ca66f99a1a5e)`	affected	code_commit	—
`[18bcbcfe9ca2308ebffb40068b51803da9315d97,ab2bfd7bec4f134b377ec42f513e90c35db94160)`	affected	code_commit	—
`[18bcbcfe9ca2308ebffb40068b51803da9315d97,766738ecf2b819e54d38763c8d1c8ae6cff14b39)`	affected	code_commit	—
`[18bcbcfe9ca2308ebffb40068b51803da9315d97,9ba62966461a8e3cc593b62c56ec62eb2d80436d)`	affected	code_commit	—
`[18bcbcfe9ca2308ebffb40068b51803da9315d97,62fc8eb1b1481051f7bab4aa93d79809053dd09f)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`2.6.25`	affected	semver	—
`[0,2.6.25)`	unaffected	generic	—
`[5.10.261,5.11.0)`	unaffected	semver	—
`[5.15.212,5.16.0)`	unaffected	semver	—
`[6.1.178,6.2.0)`	unaffected	semver	—
`[6.6.145,6.7.0)`	unaffected	semver	—
`[6.12.96,6.13.0)`	unaffected	semver	—
`[6.18.39,6.19.0)`	unaffected	semver	—
`[7.1.4,7.2.0)`	unaffected	semver	—
`[7.2-rc3,*]`	unaffected	generic	—

Found an issue or want to improve our Enrichment? You can suggest it directly by opening an issue on our dedicated GitHub repository .

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Apply a kernel update that includes the commits referenced above, ensuring the legacy USB tower driver is patched.
If an update is delayed, block the legacy driver by adding modules.blacklist=legousbtower to the kernel boot parameters or unloading the module via rmmod before the driver loads.
Isolate USB-connected devices to a dedicated VM or container with reduced privileges to contain any impact.

Generated by OpenCVE AI on August 5, 2026 at 00:59 UTC.

Tracking

Sign in to view the affected projects.

Advisories

Source	ID	Title
Debian DLA	DLA-4717-1	linux security update
Debian DLA	DLA-4720-1	linux security update
Debian DLA	DLA-4723-1	linux-6.1 security update
Debian DLA	DLA-4724-1	linux-6.12 new package

No CVSS v4.0

Attack Vector Local

Attack Complexity High

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 0.00177.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/0b57e5ddbd89df3bc367463de3d2ca66f99a1a5e
https://git.kernel.org/stable/c/11d069f85851997b4ea0adf242ed9672dc749b8f
https://git.kernel.org/stable/c/62fc8eb1b1481051f7bab4aa93d79809053dd09f
https://git.kernel.org/stable/c/6462de75d2e370c7e74dcfb7b4ae79eb5a6a55ee
https://git.kernel.org/stable/c/766738ecf2b819e54d38763c8d1c8ae6cff14b39
https://git.kernel.org/stable/c/9ba62966461a8e3cc593b62c56ec62eb2d80436d
https://git.kernel.org/stable/c/ab2bfd7bec4f134b377ec42f513e90c35db94160
https://git.kernel.org/stable/c/b4222c05066b252b451f9c8c4730b5b60824ea66
https://lore.kernel.org/linux-cve-announce/2026072515-CVE-2026-64340-1720@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-64340
https://www.cve.org/CVERecord?id=CVE-2026-64340

History

Mon, 03 Aug 2026 19:30:00 +0000

Type	Values Removed	Values Added
Weaknesses	CWE-416

Thu, 30 Jul 2026 00:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-364
References		https://lore.kernel.org/linux-cve-announce/2026072515-CVE-2026-64340-1720@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-64340 https://www.cve.org/CVERecord?id=CVE-2026-64340
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`

Tue, 28 Jul 2026 16:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-416

Sat, 25 Jul 2026 09:30:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: USB: legousbtower: fix use-after-free on disconnect race mutex_unlock() may access the mutex structure after releasing the lock and therefore cannot be used to manage lifetime of objects directly (unlike spinlocks and refcounts). [1][2] Use a kref to release the driver data to avoid use-after-free in mutex_unlock() when release() races with disconnect(). [1] a51749ab34d9 ("locking/mutex: Document that mutex_unlock() is non-atomic") [2] 2b9d9e0a9ba0 ("locking/mutex: Clarify that mutex_unlock(), and most other sleeping locks, can still use the lock object after it's unlocked")
Title		USB: legousbtower: fix use-after-free on disconnect race
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/0b57e5ddbd89df3bc367463de3d2ca66f99a1a5e https://git.kernel.org/stable/c/11d069f85851997b4ea0adf242ed9672dc749b8f https://git.kernel.org/stable/c/62fc8eb1b1481051f7bab4aa93d79809053dd09f https://git.kernel.org/stable/c/6462de75d2e370c7e74dcfb7b4ae79eb5a6a55ee https://git.kernel.org/stable/c/766738ecf2b819e54d38763c8d1c8ae6cff14b39 https://git.kernel.org/stable/c/9ba62966461a8e3cc593b62c56ec62eb2d80436d https://git.kernel.org/stable/c/ab2bfd7bec4f134b377ec42f513e90c35db94160 https://git.kernel.org/stable/c/b4222c05066b252b451f9c8c4730b5b60824ea66

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-07-25T08:50:03.896Z

Updated: 2026-07-25T08:50:03.896Z

Reserved: 2026-07-19T15:36:31.781Z

Link: CVE-2026-64340

Vulnrichment

No data.

NVD

Status : Awaiting Analysis

Published: 2026-07-25T10:17:15.983

Modified: 2026-08-11T15:00:57.447

Link: CVE-2026-64340

Redhat

Severity : Moderate

Publid Date: 2026-07-25T00:00:00Z

Links: CVE-2026-64340 - Bugzilla

OpenCVE Enrichment

Updated: 2026-08-05T01:00:07Z

Weaknesses

CWE-364
Signal Handler Race Condition

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Subscriptions

JSON object

JSON object

JSON object

JSON object

JSON object