CVE-2026-43424

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_tcm: Fix NULL pointer dereferences in nexus handling The `tpg->tpg_nexus` pointer in the USB Target driver is dynamically managed and tied to userspace configuration via ConfigFS. It can be NULL if the USB host sends requests before the nexus is fully established or immediately after it is dropped. Currently, functions like `bot_submit_command()` and the data transfer paths retrieve `tv_nexus = tpg->tpg_nexus` and immediately dereference `tv_nexus->tvn_se_sess` without any validation. If a malicious or misconfigured USB host sends a BOT (Bulk-Only Transport) command during this race window, it triggers a NULL pointer dereference, leading to a kernel panic (local DoS). This exposes an inconsistent API usage within the module, as peer functions like `usbg_submit_command()` and `bot_send_bad_response()` correctly implement a NULL check for `tv_nexus` before proceeding. Fix this by bringing consistency to the nexus handling. Add the missing `if (!tv_nexus)` checks to the vulnerable BOT command and request processing paths, aborting the command gracefully with an error instead of crashing the system.

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

Linux Kernel (具体受影响版本请参考Git提交记录)

PoC / Exploit Code

⚠ For Security Research Only

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

python

// Conceptual PoC to trigger the race condition
// This requires a malicious USB host controller or emulation.

#include <linux/usb/gadget.h>
// ... includes ...

void trigger_cve() {
    // 1. Ensure the gadget is configured but nexus is NULL/Racing
    // 2. Send a BOT command immediately
    
    struct usb_request *req;
    // ... setup request ...
    
    // Sending BOT command while tpg->tpg_nexus is NULL
    // This calls bot_submit_command() which crashes on:
    // tv_nexus = tpg->tpg_nexus;
    // tv_nexus->tvn_se_sess (Dereference NULL)
    
    // Send malicious URB
    usb_ep_queue(ep, req, GFP_KERNEL);
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43424
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43424
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43424/
[4] VulDB https://vuldb.com/cve/CVE-2026-43424
[5] https://git.kernel.org/stable/c/2a2ef846a54a06c33b5c2d4b0d918583e1e7c0b7
[6] https://git.kernel.org/stable/c/3d309b37633c4a847fc149939a2c9576f1aa1065
[7] https://git.kernel.org/stable/c/679d9535aeb15c10bce89c44102004b96624d706
[8] https://git.kernel.org/stable/c/b9b26d7f3aa288cfa54a7bc68612bab1f153f156
[9] https://git.kernel.org/stable/c/b9fde507355342a2d64225d582dc8b98ff5ecb19
[10] https://git.kernel.org/stable/c/d146f27758049fa55ae4c53785a852d3cf7a18d6
[11] https://git.kernel.org/stable/c/f962ca3b020e13d6714f27e8c36fe742441c58d1

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43424", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-08T15:16:54.497", "lastModified": "2026-05-20T18:37:33.487", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_tcm: Fix NULL pointer dereferences in nexus handling\n\nThe `tpg->tpg_nexus` pointer in the USB Target driver is dynamically\nmanaged and tied to userspace configuration via ConfigFS. It can be\nNULL if the USB host sends requests before the nexus is fully\nestablished or immediately after it is dropped.\n\nCurrently, functions like `bot_submit_command()` and the data\ntransfer paths retrieve `tv_nexus = tpg->tpg_nexus` and immediately\ndereference `tv_nexus->tvn_se_sess` without any validation. If a\nmalicious or misconfigured USB host sends a BOT (Bulk-Only Transport)\ncommand during this race window, it triggers a NULL pointer\ndereference, leading to a kernel panic (local DoS).\n\nThis exposes an inconsistent API usage within the module, as peer\nfunctions like `usbg_submit_command()` and `bot_send_bad_response()`\ncorrectly implement a NULL check for `tv_nexus` before proceeding.\n\nFix this by bringing consistency to the nexus handling. Add the\nmissing `if (!tv_nexus)` checks to the vulnerable BOT command and\nrequest processing paths, aborting the command gracefully with an\nerror instead of crashing the system."}], "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": "CWE-476"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "5.10.253", "matchCriteriaId": "69A57346-D8E9-487F-A201-B8C0896B3D73"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "6.1.167", "matchCriteriaId": "56D62904-7C85-4BED-9EC0-3982B880F72D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.130", "matchCriteriaId": "C57BB918-DF28-46B3-94F7-144176841267"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.78", "matchCriteriaId": "28D591F5-B196-4CC9-905C-DC80F116E7A8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.19", "matchCriteriaId": "D394AC60-6F28-435F-872A-CCDF384B8331"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.9", "matchCriteriaId": "E825E7C3-FEAC-4FD3-8A81-78D7387948C9"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/2a2ef846a54a06c33b5c2d4b0d918583e1e7c0b7", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/3d309b37633c4a847fc149939a2c9576f1aa1065", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/679d9535aeb15c10bce89c44102004b96624d706", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b9b26d7f3aa288cfa54a7bc68612bab1f153f156", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b9fde507355342a2d64225d582dc8b98ff5ecb19", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d146f27758049fa55ae4c53785a852d3cf7a18d6", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/f962ca3b020e13d6714f2 ... 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