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CVE-2026-31726— usb: gadget: uvc: fix NULL pointer dereference during unbind race

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于uvc在解绑竞争期间存在空指针取消引用，可能导致内核崩溃。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.16% · P5

Affected Version Matrix 22

VendorProduct Version RangeStatus
Linux Linux 1444e0568bc2c70868e7b8da5b46fc2252acc3f5< 0c00ec409d7b2bce3fcac73188b79a141db7cfda affected
4962e5a2f301d24953f17d6748d986e21566abe1< d92d1532e05b1b31d36d48765e43bf73d793d19f affected
b81ac4395bbeaf36e078dea1a48c02dd97b76235< 0587de744615628c38e33ddc1601160a5ea8c50a affected
b81ac4395bbeaf36e078dea1a48c02dd97b76235< c78e463ee134b4669579d453c81ae00795e4c19a affected
b81ac4395bbeaf36e078dea1a48c02dd97b76235< 8a1128d604c360eca135f15b882b70256a522145 affected
b81ac4395bbeaf36e078dea1a48c02dd97b76235< 1aa9356881ee4ed414bf72d0c56d915492cb5345 affected
b81ac4395bbeaf36e078dea1a48c02dd97b76235< c038ba56b92e410d1caec22b2dc68780a0b42091 affected
b81ac4395bbeaf36e078dea1a48c02dd97b76235< eba2936bbe6b752a31725a9eb5c674ecbf21ee7d affected
… +14 more rows
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I. Basic Information for CVE-2026-31726

Vulnerability Information
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Vulnerability Title
usb: gadget: uvc: fix NULL pointer dereference during unbind race
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于uvc在解绑竞争期间存在空指针取消引用，可能导致内核崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 1444e0568bc2c70868e7b8da5b46fc2252acc3f5 ~ 0c00ec409d7b2bce3fcac73188b79a141db7cfda -
Linux Linux 5.18 -

II. Public POCs for CVE-2026-31726

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III. Intelligence Information for CVE-2026-31726

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Patches & Fixes for CVE-2026-31726 (8)

Same Patch Batch · Linux · 2026-05-01 · 146 CVEs total

CVE-2026-43011 9.8 CRITICAL net/x25: Fix potential double free of skb
CVE-2026-43037 9.8 CRITICAL ip6_tunnel: clear skb2->cb[] in ip4ip6_err()
CVE-2026-31705 9.8 CRITICAL ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment
CVE-2026-43038 9.8 CRITICAL ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()
CVE-2026-43039 9.8 CRITICAL net: ti: icssg-prueth: fix missing data copy and wrong recycle in ZC RX dispatch
CVE-2026-31718 9.8 CRITICAL ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger
CVE-2026-43018 8.8 HIGH Bluetooth: hci_event: fix potential UAF in hci_le_remote_conn_param_req_evt
CVE-2026-31773 8.8 HIGH Bluetooth: SMP: derive legacy responder STK authentication from MITM state
CVE-2026-31739 8.8 HIGH crypto: tegra - Add missing CRYPTO_ALG_ASYNC
CVE-2026-31735 8.8 HIGH iommupt: Fix short gather if the unmap goes into a large mapping
CVE-2026-31717 8.8 HIGH ksmbd: validate owner of durable handle on reconnect
CVE-2026-43048 8.8 HIGH HID: core: Mitigate potential OOB by removing bogus memset()
CVE-2026-31709 8.8 HIGH smb: client: validate the whole DACL before rewriting it in cifsacl
CVE-2026-31706 8.8 HIGH ksmbd: validate num_aces and harden ACE walk in smb_inherit_dacl()
CVE-2026-31712 8.3 HIGH ksmbd: require minimum ACE size in smb_check_perm_dacl()
CVE-2026-31771 8.1 HIGH Bluetooth: hci_event: move wake reason storage into validated event handlers
CVE-2026-31779 8.1 HIGH wifi: iwlwifi: mvm: fix potential out-of-bounds read in iwl_mvm_nd_match_info_handler()
CVE-2026-43051 8.1 HIGH HID: wacom: fix out-of-bounds read in wacom_intuos_bt_irq
CVE-2026-31708 8.1 HIGH smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path
CVE-2026-31695 7.8 HIGH wifi: virt_wifi: remove SET_NETDEV_DEV to avoid use-after-free

Showing top 20 of 146 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-31726

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