CVE-2026-6784

Description

Memory safety bugs present in Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

CVSS Details

CVSS Score

7.5

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

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

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

Mozilla Firefox < 150

Mozilla Thunderbird < 150

PoC / Exploit Code

⚠ For Security Research Only

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

python

<!--
// PoC for CVE-2026-6784 (Conceptual)
// This script demonstrates a generic trigger pattern for memory corruption.
// Target: Mozilla Firefox < 150
-->

<html>
<head>
    <title>CVE-2026-6784 PoC</title>
</head>
<body>
    <h1>Testing Memory Corruption</h1>
    <script>
        function attempt_exploit() {
            // Allocating a large buffer to stress memory management
            var buffer = new ArrayBuffer(0x100000);
            var view = new DataView(buffer);
            
            console.log("[+] Attempting to trigger memory corruption...");
            
            try {
                // Simulating the condition that leads to memory safety bug
                // In a real scenario, specific API calls or DOM manipulation would be used
                for (var i = 0; i < 0x10000; i++) {
                    // Writing potentially out of bounds data
                    view.setUint32(i * 4, 0x41414141, true); 
                }
                
                // Triggering garbage collection or specific layout pass
                if (window.gc) {
                    window.gc();
                }
                
                console.log("[+] Payload delivery attempted.");
            } catch (e) {
                console.log("[-] Exception caught: " + e.message);
            }
        }

        // Trigger automatically on load
        window.onload = attempt_exploit;
    </script>
</body>
</html>

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-6784
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-6784
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-6784/
[4] VulDB https://vuldb.com/cve/CVE-2026-6784
[5] https://bugzilla.mozilla.org/buglist.cgi?bug_id=1536243%2C1745382%2C1851073%2C1893400%2C1963301%2C2001319%2C2002899%2C2012436%2C2014435%2C2016901%2C2019916%2C2020486%2C2020612%2C2020817%2C2021788%2C2022051%2C2022367%2C2022431%2C2023302%2C2023670%2C2024225%2C2024238%2C2024240%2C2024265%2C2024367%2C2024369%2C2024424%2C2024760%2C2025281%2C2025361%2C2025387%2C2025466%2C2025954%2C2025958%2C2026278%2C2026292%2C2026297%2C2026378%2C2027148%2C2027287%2C2027341%2C2027384%2C2027427%2C2027694%2C2027993%2C2028009%2C2028270%2C2028416%2C2028524%2C2029295%2C2029699%2C2029800%2C2029801
[6] https://www.mozilla.org/security/advisories/mfsa2026-30/
[7] https://www.mozilla.org/security/advisories/mfsa2026-33/

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-6784", "sourceIdentifier": "[email protected]", "published": "2026-04-21T13:16:24.020", "lastModified": "2026-05-07T16:16:22.957", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "Memory safety bugs present in Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 150 and Thunderbird 150."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.6, "impactScore": 5.9}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-125"}, {"lang": "en", "value": "CWE-416"}, {"lang": "en", "value": "CWE-787"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "versionEndExcluding": "150.0", "matchCriteriaId": "67B01D49-66FA-4C76-9EB4-2B8CD61FBEB2"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*", "versionEndExcluding": "150.0", "matchCriteriaId": "5DDDA58D-2B1E-4956-9CC2-45B3017F3F0B"}]}]}], "references": [{"url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=1536243%2C1745382%2C1851073%2C1893400%2C1963301%2C2001319%2C2002899%2C2012436%2C2014435%2C2016901%2C2019916%2C2020486%2C2020612%2C2020817%2C2021788%2C2022051%2C2022367%2C2022431%2C2023302%2C2023670%2C2024225%2C2024238%2C2024240%2C2024265%2C2024367%2C2024369%2C2024424%2C2024760%2C2025281%2C2025361%2C2025387%2C2025466%2C2025954%2C2025958%2C2026278%2C2026292%2C2026297%2C2026378%2C2027148%2C2027287%2C2027341%2C2027384%2C2027427%2C2027694%2C2027993%2C2028009%2C2028270%2C2028416%2C2028524%2C2029295%2C2029699%2C2029800%2C2029801", "source": "[email protected]"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-30/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-33/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}