CVE-2026-31726

MEDIUM EPSS 2.1%
Published May 1, 20261mo ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
Find Similar
Published May 1, 2026 1mo ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: uvc: fix NULL pointer dereference during unbind race Commit b81ac4395bbe ("usb: gadget: uvc: allow for application to cleanly shutdown") introduced two stages of synchronization waits totaling 1500ms in uvc_function_unbind() to prevent several types of kernel panics. However, this timing-based approach is insufficient during power management (PM) transitions. When the PM subsystem starts freezing user space processes, the wait_event_interruptible_timeout() is aborted early, which allows the unbind thread to proceed and nullify the gadget pointer (cdev->gadget = NULL): [ 814.123447][ T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind() [ 814.178583][ T3173] PM: suspend entry (deep) [ 814.192487][ T3173] Freezing user space processes [ 814.197668][ T947] configfs-gadget.g1 gadget.0: uvc: uvc_function_unbind no clean disconnect, wait for release When the PM subsystem resumes or aborts the suspend and tasks are restarted, the V4L2 release path is executed and attempts to access the already nullified gadget pointer, triggering a kernel panic: [ 814.292597][ C0] PM: pm_system_irq_wakeup: 479 triggered dhdpcie_host_wake [ 814.386727][ T3173] Restarting tasks ... [ 814.403522][ T4558] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000030 [ 814.404021][ T4558] pc : usb_gadget_deactivate+0x14/0xf4 [ 814.404031][ T4558] lr : usb_function_deactivate+0x54/0x94 [ 814.404078][ T4558] Call trace: [ 814.404080][ T4558] usb_gadget_deactivate+0x14/0xf4 [ 814.404083][ T4558] usb_function_deactivate+0x54/0x94 [ 814.404087][ T4558] uvc_function_disconnect+0x1c/0x5c [ 814.404092][ T4558] uvc_v4l2_release+0x44/0xac [ 814.404095][ T4558] v4l2_release+0xcc/0x130 Address the race condition and NULL pointer dereference by: 1. State Synchronization (flag + mutex) Introduce a 'func_unbound' flag in struct uvc_device. This allows uvc_function_disconnect() to safely skip accessing the nullified cdev->gadget pointer. As suggested by Alan Stern, this flag is protected by a new mutex (uvc->lock) to ensure proper memory ordering and prevent instruction reordering or speculative loads. This mutex is also used to protect 'func_connected' for consistent state management. 2. Explicit Synchronization (completion) Use a completion to synchronize uvc_function_unbind() with the uvc_vdev_release() callback. This prevents Use-After-Free (UAF) by ensuring struct uvc_device is freed after all video device resources are released.

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
2.1% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-476 NULL Pointer Dereference Memory Safety

Affected Products 13

VendorProductVersionRange
linuxlinux_kernel*≥5.10.117  –  <5.10.253
linuxlinux_kernel*≥5.15.41  –  <5.15.203
linuxlinux_kernel*≥5.18  –  <6.1.168
linuxlinux_kernel*≥6.2  –  <6.6.134
linuxlinux_kernel*≥6.7  –  <6.12.81
linuxlinux_kernel*≥6.13  –  <6.18.22
linuxlinux_kernel*≥6.19  –  <6.19.12
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any

References 8

  • git.kernel.org https://git.kernel.org/stable/c/0587de744615628c38e33ddc1601160a5ea8c50a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/0c00ec409d7b2bce3fcac73188b79a141db7cfda
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/1aa9356881ee4ed414bf72d0c56d915492cb5345
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8a1128d604c360eca135f15b882b70256a522145
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c038ba56b92e410d1caec22b2dc68780a0b42091
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c78e463ee134b4669579d453c81ae00795e4c19a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d92d1532e05b1b31d36d48765e43bf73d793d19f
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/eba2936bbe6b752a31725a9eb5c674ecbf21ee7d
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/0587de744615628c38e33ddc1601160a5ea8c50a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/0c00ec409d7b2bce3fcac73188b79a141db7cfda
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/1aa9356881ee4ed414bf72d0c56d915492cb5345
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8a1128d604c360eca135f15b882b70256a522145
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c038ba56b92e410d1caec22b2dc68780a0b42091
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c78e463ee134b4669579d453c81ae00795e4c19a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/d92d1532e05b1b31d36d48765e43bf73d793d19f
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/eba2936bbe6b752a31725a9eb5c674ecbf21ee7d
    Patch