CVE-2026-64331 - Vulnerability Details

- usbip: vudc: fix NULL deref in vep_dequeue()

Description

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

usbip: vudc: fix NULL deref in vep_dequeue()

vep_alloc_request() wasn't initializing vrequest->udc, so cancellations
on the FunctionFS AIO path were arriving in vep_dequeue without a valid
UDC reference.

Since vrequest->udc is never actually properly used anywhere, we opt to
remove it, and update vep_dequeue to obtain a reference to the udc with
ep_to_vudc(), consistent with the other vep_ ops.

AFAICT this bug has existed for ~10 years. Seems that nobody has really
stressed the FunctionFS AIO path on usbip's vudc.

I tested this fix in a QEMU aarch64 guest driving FunctionFS endpoints
via AIO. Before the fix, running `usbip attach` from the host would
cause the guest to oops with the following backtrace:

Call trace:
vep_dequeue+0x1c/0xe4 (P)
usb_ep_dequeue+0x14/0x20
ffs_aio_cancel+0x24/0x34
__arm64_sys_io_cancel+0xb0/0x124
do_el0_svc+0x68/0x100
el0_svc+0x18/0x5c
el0t_64_sync_handler+0x98/0xdc
el0t_64_sync+0x154/0x158

Published: 2026-07-25

Score: n/a

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

This vulnerability is a NULL dereference in the usbip vudc driver that occurs when the FunctionFS AIO path attempts to cancel a request. The bug can cause the kernel to oops, resulting in a system crash. The nature of the flaw is a classic null pointer dereference (CWE‑476) and it does not provide an attacker with code execution or information disclosure. Its primary impact is a denial of service that occurs when usbip operations that exercise FunctionFS AIO are performed.

Affected Systems

Any Linux kernel that implements the usbip vudc driver may be affected. The exact kernel versions are not specified, but the bug has existed for roughly ten years and is likely present in older releases that include usbip FunctionFS support.

Risk and Exploitability

The EPSS score is recorded as less than 1 %, indicating a very low likelihood of exploitation in the wild. The vulnerability is not currently listed in CISA’s KEV catalog. Based on the description, it is inferred that the crash can be triggered by invoking usbip attach to a guest that uses FunctionFS endpoints via AIO, meaning that an attacker with the ability to control such USBIP traffic could force a system reboot. Because the vulnerability only causes a kernel crash, the attack vector is inferred to be local or remote through USBIP traffic, and there are no known successful exploits. The CVSS score is not disclosed, but the impact rating is high in terms of availability.

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
`b6a0ca11186759ad7045d68a5447b1e89f658384`	affected	< 9858c91d9ee6a13c45311569039413729fc9b757
`b6a0ca11186759ad7045d68a5447b1e89f658384`	affected	< 1226293ec9bed3d4cc5b05eeeb811d315ca51652
`b6a0ca11186759ad7045d68a5447b1e89f658384`	affected	< 3750f75f29f99c0223601e2ee73ad084adec47bd
`b6a0ca11186759ad7045d68a5447b1e89f658384`	affected	< d0ebf9cc7c2ddf95a7cfc654b940bdacb7edde97
`b6a0ca11186759ad7045d68a5447b1e89f658384`	affected	< 0025276175fbbe0dcbf3f84d090b0adee769e9d9
`b6a0ca11186759ad7045d68a5447b1e89f658384`	affected	< 347b59e9f96719d89b6ef555d02a18ada1a5846f
`b6a0ca11186759ad7045d68a5447b1e89f658384`	affected	< 0443e4416aa1ee97748d1ed904eaf3352c60045e
`b6a0ca11186759ad7045d68a5447b1e89f658384`	affected	< c5371e0b91b24159a3ebaa61e70b0980bcf03c0a

Linux

affected

Version	Status	Constraints
`4.7`	affected	—
`0`	unaffected	< 4.7
`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
`[b6a0ca11186759ad7045d68a5447b1e89f658384,9858c91d9ee6a13c45311569039413729fc9b757)`	affected	code_commit	—
`[b6a0ca11186759ad7045d68a5447b1e89f658384,1226293ec9bed3d4cc5b05eeeb811d315ca51652)`	affected	code_commit	—
`[b6a0ca11186759ad7045d68a5447b1e89f658384,3750f75f29f99c0223601e2ee73ad084adec47bd)`	affected	code_commit	—
`[b6a0ca11186759ad7045d68a5447b1e89f658384,d0ebf9cc7c2ddf95a7cfc654b940bdacb7edde97)`	affected	code_commit	—
`[b6a0ca11186759ad7045d68a5447b1e89f658384,0025276175fbbe0dcbf3f84d090b0adee769e9d9)`	affected	code_commit	—
`[b6a0ca11186759ad7045d68a5447b1e89f658384,347b59e9f96719d89b6ef555d02a18ada1a5846f)`	affected	code_commit	—
`[b6a0ca11186759ad7045d68a5447b1e89f658384,0443e4416aa1ee97748d1ed904eaf3352c60045e)`	affected	code_commit	—
`[b6a0ca11186759ad7045d68a5447b1e89f658384,c5371e0b91b24159a3ebaa61e70b0980bcf03c0a)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`4.7`	affected	generic	—
`[0,4.7)`	unaffected	generic	—
`[5.10.261,5.10.*]`	unaffected	generic	—
`[5.15.212,5.15.*]`	unaffected	generic	—
`[6.1.178,6.1.*]`	unaffected	generic	—
`[6.6.145,6.6.*]`	unaffected	generic	—
`[6.12.96,6.12.*]`	unaffected	generic	—
`[6.18.39,6.18.*]`	unaffected	generic	—
`[7.1.4,7.1.*]`	unaffected	generic	—
`[7.2-rc3,*]`	unaffected	generic	—

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Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Upgrade the Linux kernel to a version that includes the commit adding ep_to_vudc() in vep_dequeue
If immediate upgrading is not possible, disable the usbip vudc driver or unload the usbip module to avoid crashes
If the system relies on FunctionFS AIO, reconfigure to disable AIO or use an alternate transport until the kernel is patched

Generated by OpenCVE AI on August 3, 2026 at 19:12 UTC.

Tracking

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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

No CVSS v3.1

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/0025276175fbbe0dcbf3f84d090b0adee769e9d9
https://git.kernel.org/stable/c/0443e4416aa1ee97748d1ed904eaf3352c60045e
https://git.kernel.org/stable/c/1226293ec9bed3d4cc5b05eeeb811d315ca51652
https://git.kernel.org/stable/c/347b59e9f96719d89b6ef555d02a18ada1a5846f
https://git.kernel.org/stable/c/3750f75f29f99c0223601e2ee73ad084adec47bd
https://git.kernel.org/stable/c/9858c91d9ee6a13c45311569039413729fc9b757
https://git.kernel.org/stable/c/c5371e0b91b24159a3ebaa61e70b0980bcf03c0a
https://git.kernel.org/stable/c/d0ebf9cc7c2ddf95a7cfc654b940bdacb7edde97
https://lore.kernel.org/linux-cve-announce/2026072513-CVE-2026-64331-7a76@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-64331
https://www.cve.org/CVERecord?id=CVE-2026-64331

History

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

Type	Values Removed	Values Added
Weaknesses		CWE-476
References		https://lore.kernel.org/linux-cve-announce/2026072513-CVE-2026-64331-7a76@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-64331 https://www.cve.org/CVERecord?id=CVE-2026-64331

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

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: usbip: vudc: fix NULL deref in vep_dequeue() vep_alloc_request() wasn't initializing vrequest->udc, so cancellations on the FunctionFS AIO path were arriving in vep_dequeue without a valid UDC reference. Since vrequest->udc is never actually properly used anywhere, we opt to remove it, and update vep_dequeue to obtain a reference to the udc with ep_to_vudc(), consistent with the other vep_ ops. AFAICT this bug has existed for ~10 years. Seems that nobody has really stressed the FunctionFS AIO path on usbip's vudc. I tested this fix in a QEMU aarch64 guest driving FunctionFS endpoints via AIO. Before the fix, running `usbip attach` from the host would cause the guest to oops with the following backtrace: Call trace: vep_dequeue+0x1c/0xe4 (P) usb_ep_dequeue+0x14/0x20 ffs_aio_cancel+0x24/0x34 __arm64_sys_io_cancel+0xb0/0x124 do_el0_svc+0x68/0x100 el0_svc+0x18/0x5c el0t_64_sync_handler+0x98/0xdc el0t_64_sync+0x154/0x158
Title		usbip: vudc: fix NULL deref in vep_dequeue()
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/0025276175fbbe0dcbf3f84d090b0adee769e9d9 https://git.kernel.org/stable/c/0443e4416aa1ee97748d1ed904eaf3352c60045e https://git.kernel.org/stable/c/1226293ec9bed3d4cc5b05eeeb811d315ca51652 https://git.kernel.org/stable/c/347b59e9f96719d89b6ef555d02a18ada1a5846f https://git.kernel.org/stable/c/3750f75f29f99c0223601e2ee73ad084adec47bd https://git.kernel.org/stable/c/9858c91d9ee6a13c45311569039413729fc9b757 https://git.kernel.org/stable/c/c5371e0b91b24159a3ebaa61e70b0980bcf03c0a https://git.kernel.org/stable/c/d0ebf9cc7c2ddf95a7cfc654b940bdacb7edde97

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-07-25T08:49:58.370Z

Updated: 2026-07-25T08:49:58.370Z

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

Link: CVE-2026-64331

Vulnrichment

No data.

NVD

Status : Awaiting Analysis

Published: 2026-07-25T10:17:14.813

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

Link: CVE-2026-64331

Redhat

Severity :

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

Links: CVE-2026-64331 - Bugzilla

OpenCVE Enrichment

Updated: 2026-08-03T19:15:04Z

Weaknesses

CWE-476
NULL Pointer Dereference

Impact

Affected Systems

Risk and Exploitability

Tracking

Subscriptions

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