CVE-2026-106446
Handlebars provides the power necessary to let users build semantic templates. From 4.0.0 until 4.7.10, Handlebars.compile() and Handlebars.precompile() accept pre-parsed AST objects while validating only selected PathExpression, NumberLiteral, and BooleanLiteral values. This issue bypasses the AST validation introduced in version 4.7.9 for CVE-2026-33937.
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An attacker who can supply an object instead of a template string can place JavaScript expressions in unchecked values such as Program.blockParams.length, a non-PathExpression parameter depth, a non-string StringLiteral.value, or a non-string PathExpression.original. The compiler emits those values into generated JavaScript, causing code execution in the server process when compile output renders or wherever precompile output is loaded. Applications that pass only template strings are not affected. This issue is fixed in version 4.7.10.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 9.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.64%
- Percentil entre todas las CVEs puntuadas: 49
- Fecha de la puntuación: 7/10/2026
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 access90 % - Impacto principal
T1059Command and Scripting Interpreterexecution95 % - Impacto secundario
T1068Exploitation for Privilege Escalationprivilege escalation70 %
AV:N/PR:N/UI:N indica explotación remota sin privilegios previos (T1190). La vulnerabilidad permite inyectar JavaScript en el AST compilado, causando ejecución de código (T1059) con impacto de confidencialidad, integridad y disponibilidad (CVSS:3.1/C:H/I:H/A:H). Potencial escalada si se ejecuta en p
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-94, CWE-843
Referencias
- https://github.com/handlebars-lang/handlebars.js/commit/703fdcc5fd6cc8d1cc0c33cc19de40c467c4b8d2
- https://github.com/handlebars-lang/handlebars.js/pull/2185
- https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.10
- https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-8r5x-fm3f-whwj
JSON original (NVD)
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{
"id": "CVE-2026-106446",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Secondary",
"source": "security-advisories@github.com",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 9.8,
"attackVector": "NETWORK",
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "NONE",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"exploitabilityScore": 3.9
}
]
},
"affected": [
{
"source": "security-advisories@github.com",
"affectedData": [
{
"vendor": "handlebars-lang",
"product": "handlebars.js",
"versions": [
{
"status": "affected",
"version": ">= 4.0.0, < 4.7.10"
}
]
}
]
}
],
"published": "2026-10-06T20:17:26.430",
"references": [
{
"url": "https://github.com/handlebars-lang/handlebars.js/commit/703fdcc5fd6cc8d1cc0c33cc19de40c467c4b8d2",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/handlebars-lang/handlebars.js/pull/2185",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.10",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-8r5x-fm3f-whwj",
"source": "security-advisories@github.com"
}
],
"vulnStatus": "Awaiting Analysis",
"weaknesses": [
{
"type": "Primary",
"source": "security-advisories@github.com",
"description": [
{
"lang": "en",
"value": "CWE-94"
},
{
"lang": "en",
"value": "CWE-843"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Handlebars provides the power necessary to let users build semantic templates. From 4.0.0 until 4.7.10, Handlebars.compile() and Handlebars.precompile() accept pre-parsed AST objects while validating only selected PathExpression, NumberLiteral, and BooleanLiteral values. This issue bypasses the AST validation introduced in version 4.7.9 for CVE-2026-33937. An attacker who can supply an object instead of a template string can place JavaScript expressions in unchecked values such as Program.blockParams.length, a non-PathExpression parameter depth, a non-string StringLiteral.value, or a non-string PathExpression.original. The compiler emits those values into generated JavaScript, causing code execution in the server process when compile output renders or wherever precompile output is loaded. Applications that pass only template strings are not affected. This issue is fixed in version 4.7.10."
}
],
"lastModified": "2026-10-07T13:58:29.527",
"sourceIdentifier": "security-advisories@github.com"
}