CVE-2026-71851
crypto-js is a JavaScript library of crypto standards. Versions of crypto-js prior to 4.0.0 generate randomness in CryptoJS.lib.WordArray.random() using a custom variation of the Multiply-With-Carry pseudorandom number generator, seeded from Math.random(), instead of a cryptographically secure source. This generator was introduced in version 3.1.2-4 and remained present in nearly every 3.x release.
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Nominal requests for 128 or 256 bits of entropy through this function produce effective search spaces of approximately 2 to the 39th and 2 to the 47th possibilities, small enough to enumerate on commodity hardware. Downstream wallet applications that used CryptoJS.lib.WordArray.random() as the entropy source for BIP39 recovery phrases are affected, and an attacker who enumerates the reduced output space can recover the resulting private keys and control the associated funds. This issue is fixed in version 4.0.0.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- Puntuación base: 9
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.55%
- Percentil entre todas las CVEs puntuadas: 44
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1190Exploit Public-Facing Applicationinitial access75 % - Impacto principal
T1552.007Container APIcredential access85 %
Vulnerabilidad en librería JavaScript expuesta en red (T1190). La generación débil de números aleatorios en crypto-js permite enumerar espacios de 2^39-2^47, comprometiendo frases de recuperación BIP39 y claves privadas de carteras, viabilizando robo de credenciales (T1552.007, T1078.004).
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
CWE
- CWE-331, CWE-334, CWE-338
Referencias
JSON original (NVD)
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{
"id": "CVE-2026-71851",
"cveTags": [],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-71851",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "poc"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"version": "2.0.3",
"timestamp": "2026-08-08T03:05:26.687602Z"
}
}
],
"cvssMetricV31": [
{
"type": "Secondary",
"source": "security-advisories@github.com",
"cvssData": {
"scope": "CHANGED",
"version": "3.1",
"baseScore": 9,
"attackVector": "NETWORK",
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "HIGH",
"availabilityImpact": "HIGH",
"privilegesRequired": "NONE",
"confidentialityImpact": "HIGH"
},
"impactScore": 6,
"exploitabilityScore": 2.2
}
]
},
"affected": [
{
"source": "security-advisories@github.com",
"affectedData": [
{
"vendor": "brix",
"product": "crypto-js",
"versions": [
{
"status": "affected",
"version": "< 4.0.0"
}
]
}
]
}
],
"published": "2026-08-07T19:18:54.390",
"references": [
{
"url": "https://github.com/brix/crypto-js/commit/b405ff597fb3ac76a7bdfbc72dca10ba1079b1d5",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/brix/crypto-js/security/advisories/GHSA-rg76-677x-56q9",
"source": "security-advisories@github.com"
},
{
"url": "https://www.coinspect.com/blog/ill-bloom-investigation",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/brix/crypto-js/security/advisories/GHSA-rg76-677x-56q9",
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
}
],
"vulnStatus": "Deferred",
"weaknesses": [
{
"type": "Secondary",
"source": "security-advisories@github.com",
"description": [
{
"lang": "en",
"value": "CWE-331"
},
{
"lang": "en",
"value": "CWE-334"
},
{
"lang": "en",
"value": "CWE-338"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "crypto-js is a JavaScript library of crypto standards. Versions of crypto-js prior to 4.0.0 generate randomness in CryptoJS.lib.WordArray.random() using a custom variation of the Multiply-With-Carry pseudorandom number generator, seeded from Math.random(), instead of a cryptographically secure source. This generator was introduced in version 3.1.2-4 and remained present in nearly every 3.x release. Nominal requests for 128 or 256 bits of entropy through this function produce effective search spaces of approximately 2 to the 39th and 2 to the 47th possibilities, small enough to enumerate on commodity hardware. Downstream wallet applications that used CryptoJS.lib.WordArray.random() as the entropy source for BIP39 recovery phrases are affected, and an attacker who enumerates the reduced output space can recover the resulting private keys and control the associated funds. This issue is fixed in version 4.0.0."
}
],
"lastModified": "2026-09-09T21:02:22.660",
"sourceIdentifier": "security-advisories@github.com"
}