CVE-2018-5163
Status: ModifiedHigh (8.1)—
If a malicious attacker has used another vulnerability to gain full control over a content process, they may be able to replace the alternate data resources stored in the JavaScript Start-up Bytecode Cache (JSBC) for other JavaScript code. If the parent process then runs this replaced code, the executed script would be run with the parent process' privileges, escaping the sandbox on content processes. This vulnerability affects Firefox < 60.
CVSS
- Version: 3.0
- Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Base score: 8.1
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days: 2.09%
- Percentile among all scored CVEs: 81
- Score date: 10/10/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (2)
CWEs
- CWE-281
References
- http://www.securityfocus.com/bid/104139
- http://www.securitytracker.com/id/1040896
- https://bugzilla.mozilla.org/show_bug.cgi?id=1426353
- https://usn.ubuntu.com/3645-1/
- https://www.mozilla.org/security/advisories/mfsa2018-11/
- http://www.securityfocus.com/bid/104139
- http://www.securitytracker.com/id/1040896
- https://bugzilla.mozilla.org/show_bug.cgi?id=1426353
- https://usn.ubuntu.com/3645-1/
- https://www.mozilla.org/security/advisories/mfsa2018-11/
Raw JSON (NVD)
Show
{
"id": "CVE-2018-5163",
"cveTags": [],
"metrics": {
"cvssMetricV2": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"cvssData": {
"version": "2.0",
"baseScore": 5.1,
"accessVector": "NETWORK",
"vectorString": "AV:N/AC:H/Au:N/C:P/I:P/A:P",
"authentication": "NONE",
"integrityImpact": "PARTIAL",
"accessComplexity": "HIGH",
"availabilityImpact": "PARTIAL",
"confidentialityImpact": "PARTIAL"
},
"acInsufInfo": false,
"impactScore": 6.4,
"baseSeverity": "MEDIUM",
"obtainAllPrivilege": false,
"exploitabilityScore": 4.9,
"obtainUserPrivilege": false,
"obtainOtherPrivilege": false,
"userInteractionRequired": false
}
],
"cvssMetricV30": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.0",
"baseScore": 8.1,
"attackVector": "NETWORK",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "HIGH",
"availabilityImpact": "HIGH",
"privilegesRequired": "NONE",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"exploitabilityScore": 2.2
}
]
},
"affected": [
{
"source": "security@mozilla.org",
"affectedData": [
{
"vendor": "Mozilla",
"product": "Firefox",
"versions": [
{
"status": "affected",
"version": "unspecified",
"lessThan": "60",
"versionType": "custom"
}
]
}
]
}
],
"published": "2018-06-11T21:29:15.517",
"references": [
{
"url": "http://www.securityfocus.com/bid/104139",
"tags": [
"Third Party Advisory",
"VDB Entry"
],
"source": "security@mozilla.org"
},
{
"url": "http://www.securitytracker.com/id/1040896",
"tags": [
"Third Party Advisory",
"VDB Entry"
],
"source": "security@mozilla.org"
},
{
"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1426353",
"tags": [
"Issue Tracking",
"Permissions Required",
"Vendor Advisory"
],
"source": "security@mozilla.org"
},
{
"url": "https://usn.ubuntu.com/3645-1/",
"tags": [
"Third Party Advisory"
],
"source": "security@mozilla.org"
},
{
"url": "https://www.mozilla.org/security/advisories/mfsa2018-11/",
"tags": [
"Vendor Advisory"
],
"source": "security@mozilla.org"
},
{
"url": "http://www.securityfocus.com/bid/104139",
"tags": [
"Third Party Advisory",
"VDB Entry"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "http://www.securitytracker.com/id/1040896",
"tags": [
"Third Party Advisory",
"VDB Entry"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1426353",
"tags": [
"Issue Tracking",
"Permissions Required",
"Vendor Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://usn.ubuntu.com/3645-1/",
"tags": [
"Third Party Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://www.mozilla.org/security/advisories/mfsa2018-11/",
"tags": [
"Vendor Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
}
],
"vulnStatus": "Modified",
"weaknesses": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "CWE-281"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "If a malicious attacker has used another vulnerability to gain full control over a content process, they may be able to replace the alternate data resources stored in the JavaScript Start-up Bytecode Cache (JSBC) for other JavaScript code. If the parent process then runs this replaced code, the executed script would be run with the parent process' privileges, escaping the sandbox on content processes. This vulnerability affects Firefox < 60."
},
{
"lang": "es",
"value": "Si un atacante malicioso ha utilizado otra vulnerabilidad para obtener control total sobre un proceso de contenido, es posible que pueda reemplazar los recursos de datos alternativos almacenados en el JSBC (JavaScript Start-up Bytecode Cache) por otro código JavaScript. Si el proceso padre ejecuta este código reemplazado, el script ejecutado se ejecutaría con los privilegios del proceso padre, escapando del sandbox en los procesos de contenido. Esta vulnerabilidad afecta a las versiones anteriores a la 60 de Firefox."
}
],
"lastModified": "2026-06-17T01:59:44.950",
"configurations": [
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*",
"vulnerable": true,
"matchCriteriaId": "B5A6F2F3-4894-4392-8296-3B8DD2679084"
},
{
"criteria": "cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*",
"vulnerable": true,
"matchCriteriaId": "F7016A2A-8365-4F1A-89A2-7A19F2BCAE5B"
},
{
"criteria": "cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "9070C9D8-A14A-467F-8253-33B966C16886"
},
{
"criteria": "cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*",
"vulnerable": true,
"matchCriteriaId": "23A7C53F-B80F-4E6A-AFA9-58EEA84BE11D"
}
],
"operator": "OR"
}
]
},
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "1AD89C37-DC57-40D3-80CE-5126A6C142E8",
"versionEndExcluding": "60.0"
}
],
"operator": "OR"
}
]
}
],
"sourceIdentifier": "security@mozilla.org"
}