CVE-2026-23388

Description

In the Linux kernel, the following vulnerability has been resolved: Squashfs: check metadata block offset is within range Syzkaller reports a "general protection fault in squashfs_copy_data" This is ultimately caused by a corrupted index look-up table, which produces a negative metadata block offset. This is subsequently passed to squashfs_copy_data (via squashfs_read_metadata) where the negative offset causes an out of bounds access. The fix is to check that the offset is within range in squashfs_read_metadata. This will trap this and other cases.

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 (Versions prior to commits listed in references)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC Concept for CVE-2026-23388
 * This code demonstrates the concept of mounting a crafted filesystem.
 * Actual exploitation requires a specific malformed Squashfs image.
 */

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

int main() {
    // In a real scenario, 'malicious.img' would be a Squashfs image
    // with a corrupted index table causing negative offsets.
    const char *source = "malicious_cve_2026_23388.img";
    const char *target = "/mnt/squashfs_test";

    // Create mount point
    mkdir(target, 0777);

    printf("[+] Attempting to mount malicious image to trigger OOB access...\n");

    // The vulnerability is triggered during the mount syscall processing
    // inside the kernel when it parses the metadata.
    if (mount(source, target, "squashfs", MS_RDONLY, NULL) == 0) {
        printf("[!] Mount successful. Vulnerability may have been triggered in kernel.\n");
        umount(target);
    } else {
        perror("[-] Mount failed");
    }

    rmdir(target);
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-23388
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-23388
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-23388/
[4] VulDB https://vuldb.com/cve/CVE-2026-23388
[5] https://git.kernel.org/stable/c/01ee0bcc29864b78249308e8b35042b09bbf5fe3
[6] https://git.kernel.org/stable/c/0c8ab092aec3ac4294940054772d30b511b16713
[7] https://git.kernel.org/stable/c/3b9499e7d677dd4366239a292238489a804936b2
[8] https://git.kernel.org/stable/c/3f68a9457a6190814377577374da75f872e0a013
[9] https://git.kernel.org/stable/c/60f679f643f3f36a8571ea585e4ce5d93ef952b5
[10] https://git.kernel.org/stable/c/6b847d65f5b0065e02080c61fad93d57d6686383
[11] https://git.kernel.org/stable/c/9e9fa5ad37c9cbad73c165c7ff1e76e650825e7c
[12] https://git.kernel.org/stable/c/fdb24a820a5832ec4532273282cbd4f22c291a0d

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-23388", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-03-25T11:16:39.280", "lastModified": "2026-04-24T18:45:22.870", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSquashfs: check metadata block offset is within range\n\nSyzkaller reports a \"general protection fault in squashfs_copy_data\"\n\nThis is ultimately caused by a corrupted index look-up table, which\nproduces a negative metadata block offset.\n\nThis is subsequently passed to squashfs_copy_data (via\nsquashfs_read_metadata) where the negative offset causes an out of bounds\naccess.\n\nThe fix is to check that the offset is within range in\nsquashfs_read_metadata. This will trap this and other cases."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nSquashfs: comprobar que el desplazamiento del bloque de metadatos está dentro del rango\n\nSyzkaller informa de un 'fallo de protección general en squashfs_copy_data'\n\nEsto es causado en última instancia por una tabla de búsqueda de índices corrupta, que produce un desplazamiento de bloque de metadatos negativo.\n\nEsto se pasa posteriormente a squashfs_copy_data (a través de squashfs_read_metadata) donde el desplazamiento negativo causa un acceso fuera de límites.\n\nLa solución es comprobar que el desplazamiento está dentro del rango en squashfs_read_metadata. Esto atrapará este y otros casos."}], "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": "2.6.29.1", "versionEndExcluding": "5.10.253", "matchCriteriaId": "D4949E9B-FE71-4F60-A00E-27E325AA7589"}, {"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": "6.12.77", "matchCriteriaId": "B3D12E00-E42D-4056-B354-BAD4903C03A5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.17", "matchCriteriaId": "A5E006E4-59C7-43C1-9231-62A72219F2BA"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.7", "matchCriteriaId": "69245D10-0B71-485E-80C3-A64F077004D3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:2.6.29:-:*:*:*:*:*:*", "matchCriteriaId": "EE6EED15-2E34-47D9-8619-78B03F2E294F"}, {"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/01ee0bcc29864b78249308e8b35042b09bbf5fe3", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", " ... 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