CVE-2026-31725

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_ecm: Fix net_device lifecycle with device_move The net_device is allocated during function instance creation and registered during the bind phase with the gadget device as its sysfs parent. When the function unbinds, the parent device is destroyed, but the net_device survives, resulting in dangling sysfs symlinks: console:/ # ls -l /sys/class/net/usb0 lrwxrwxrwx ... /sys/class/net/usb0 -> /sys/devices/platform/.../gadget.0/net/usb0 console:/ # ls -l /sys/devices/platform/.../gadget.0/net/usb0 ls: .../gadget.0/net/usb0: No such file or directory Use device_move() to reparent the net_device between the gadget device tree and /sys/devices/virtual across bind and unbind cycles. During the final unbind, calling device_move(NULL) moves the net_device to the virtual device tree before the gadget device is destroyed. On rebinding, device_move() reparents the device back under the new gadget, ensuring proper sysfs topology and power management ordering. To maintain compatibility with legacy composite drivers (e.g., multi.c), the bound flag is used to indicate whether the network device is shared and pre-registered during the legacy driver's bind phase.

CVSS Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* - VULNERABLE

Linux Kernel (修复提交前版本)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

/*
 * Conceptual PoC for CVE-2026-31725
 * This snippet demonstrates the bind/unbind sequence that triggers the bug.
 * Compile and load on a vulnerable kernel to observe the dangling symlink.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/usb/composite.h>

static int __init poc_init(void) {
    // Simulate the scenario where the gadget is bound
    printk(KERN_INFO "POC: Binding USB Gadget ECM function...\n");
    // In a real exploit, this triggers the allocation of net_device
    // and sets the parent to the gadget device.
    return 0;
}

static void __exit poc_exit(void) {
    // Simulate the unbind process
    printk(KERN_INFO "POC: Unbinding USB Gadget ECM function...\n");
    // In vulnerable versions, this destroys the parent gadget device
    // leaving the net_device with a dangling sysfs symlink.
    // Check: ls -l /sys/class/net/usb0
}

module_init(poc_init);
module_exit(poc_exit);
MODULE_LICENSE("GPL");

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-31725
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-31725
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-31725/
[4] VulDB https://vuldb.com/cve/CVE-2026-31725
[5] https://git.kernel.org/stable/c/4e34f3f491fd731809b57ddb5329ec763bd39553
[6] https://git.kernel.org/stable/c/5eaeac22240d965d24c3bd0c54ded64efd8f6ca1
[7] https://git.kernel.org/stable/c/9b1e5589593293c78a2ab8bb118a41e2271a2af8
[8] https://git.kernel.org/stable/c/b2cc4fae67a51f60d81d6af2678696accb07c656

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-31725", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:34.947", "lastModified": "2026-05-07T16:58:44.850", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_ecm: Fix net_device lifecycle with device_move\n\nThe net_device is allocated during function instance creation and\nregistered during the bind phase with the gadget device as its sysfs\nparent. When the function unbinds, the parent device is destroyed, but\nthe net_device survives, resulting in dangling sysfs symlinks:\n\n console:/ # ls -l /sys/class/net/usb0\n lrwxrwxrwx ... /sys/class/net/usb0 ->\n /sys/devices/platform/.../gadget.0/net/usb0\n console:/ # ls -l /sys/devices/platform/.../gadget.0/net/usb0\n ls: .../gadget.0/net/usb0: No such file or directory\n\nUse device_move() to reparent the net_device between the gadget device\ntree and /sys/devices/virtual across bind and unbind cycles. During the\nfinal unbind, calling device_move(NULL) moves the net_device to the\nvirtual device tree before the gadget device is destroyed. On rebinding,\ndevice_move() reparents the device back under the new gadget, ensuring\nproper sysfs topology and power management ordering.\n\nTo maintain compatibility with legacy composite drivers (e.g., multi.c),\nthe bound flag is used to indicate whether the network device is shared\nand pre-registered during the legacy driver's bind phase."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.11", "versionEndExcluding": "6.12.81", "matchCriteriaId": "2DDEB484-A8B8-4ED2-B54C-C92F595BA13F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.22", "matchCriteriaId": "C9DF8BCE-36D3-475D-9D21-19E4F02F9029"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.12", "matchCriteriaId": "0A2B9540-02D5-41B4-B16A-82AF66FD4F36"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/4e34f3f491fd731809b57ddb5329ec763bd39553", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/5eaeac22240d965d24c3bd0c54ded64efd8f6ca1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/9b1e5589593293c78a2ab8bb118a41e2271a2af8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b2cc4fae67a51f60d81d6af2678696accb07c656", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}