What’s Vulnerable › Vulnerabilities

CVE-2026-31728: usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop

• Severity: medium (CVSS 4.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-01 · updated 2026-06-17
• Weakness: CWE-362

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop A race condition between gether_disconnect() and eth_stop() leads to a NULL pointer dereference. Specifically, if eth_stop() is triggered concurrently while gether_disconnect() is tearing down the endpoints, eth_stop() attempts to access the cleared endpoint descriptor, causing the following NPE: Unable to handle kernel NULL pointer dereference Call trace: __dwc3_gadget_ep_enable+0x60/0x788 dwc3_gadget_ep_enable+0x70/0xe4 usb_ep_enable+0x60/0x15c eth_stop+0xb8/0x108 Because eth_stop() crashes while holding the dev->lock, the thread running gether_disconnect() fails to acquire the same lock and spins forever, resulting in a hardlockup: Core - Debugging Information for Hardlockup core(7) Call trace: queued_spin_lock_slowpath+0x94/0x488 _raw_spin_lock+0x64/0x6c gether_disconnect+0x19c/0x1e8 ncm_set_alt+0x68/0x1a0 composite_setup+0x6a0/0xc50 The root cause is that the clearing of dev->port_usb in gether_disconnect() is delayed until the end of the function. Move the clearing of dev->port_usb to the very beginning of gether_disconnect() while holding dev->lock. This cuts off the link immediately, ensuring eth_stop() will see dev->port_usb as NULL and safely bail out.

Affected products

• Linux kernel: from 2.6.27 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.169; from 6.2 before 6.6.134; from 6.7 before 6.12.81; from 6.13 before 6.18.22 — fixed in 5.10.253, 5.15.203, 6.1.169, 6.12.81, 6.18.22, 6.19.12

How to fix

Upgrade to a fixed version: Linux kernel 5.10.253, 5.15.203, 6.1.169, 6.12.81. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/6ad77458637b78ec655e3da5f112c862e6690a9d
• https://git.kernel.org/stable/c/8ff689edfeceb5e3ec1623e09af2b2aa0f1098a8
• https://git.kernel.org/stable/c/a259ba0bce3b192c04334499690372a250f7d0b1
• https://git.kernel.org/stable/c/bbb09bb89ffa571475f66daca9482b974cd29d6a
• https://git.kernel.org/stable/c/e1e7a66584bf0aff3becb73c19fa31527889fc9e
• https://git.kernel.org/stable/c/e1eabb072c75681f78312c484ccfffb7430f206e
• https://git.kernel.org/stable/c/f02980594deef751e42133714aee25228f1494c6
• https://git.kernel.org/stable/c/f6813c2b2ae78def76b69e0f9d72f80e4a1c4aca

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