CVE-2026-92087
@fastify/auth is a Fastify plugin that composes multiple authentication and authorization strategies into a single route guard. In versions 5.0.0 through 5.1.0, when strategies are composed with the relation "or" option together with the run "all" option and one entry is a nested array acting as an AND group, the group is evaluated in an order-dependent way: an earlier failing check is silently dropped and the group's result becomes the outcome of its last check.
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As a result, a request that satisfies only the last member of an AND group, for example an attacker who holds a valid API key but is not an administrator, is authorized instead of rejected, and a related order-dependent bypass affects the mirror configuration where the top-level relation is "and" and a nested group uses "or". The issue is fixed in @fastify/auth 5.1.1, and users should upgrade to 5.1.1 or later. As a workaround, omit the run "all" option where it is not required, order each AND group so its stricter check is evaluated last, or replace nested AND groups with an explicit top-level "and" composition.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
- Puntuación base: 8.1
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.47%
- Percentil entre todas las CVEs puntuadas: 39
- Fecha de la puntuación: 3/10/2026
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
T1210Exploitation of Remote Serviceslateral movement75 % - Impacto principal
T1078Valid Accountsstealth · persistence · privilege escalation · initial access80 % - Impacto secundario
T1548Abuse Elevation Control Mechanismprivilege escalation70 %
Bypass de autenticación/autorización en plugin Fastify (AV:N/PR:L) permite acceso no autorizado con credenciales parciales. Evaluación order-dependent de estrategias AND/OR permite eludir checks de seguridad.
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-285, CWE-697
Referencias
JSON original (NVD)
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"id": "CVE-2026-92087",
"cveTags": [],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"id": "CVE-2026-92087",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"version": "2.0.3",
"timestamp": "2026-09-17T19:10:08.336484Z"
}
}
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"cvssMetricV31": [
{
"type": "Secondary",
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"version": "3.1",
"baseScore": 8.1,
"attackVector": "NETWORK",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "NONE",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.2,
"exploitabilityScore": 2.8
}
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"affected": [
{
"source": "ce714d77-add3-4f53-aff5-83d477b104bb",
"affectedData": [
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"vendor": "@fastify/auth",
"product": "@fastify/auth",
"versions": [
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"status": "affected",
"version": "5.0.0",
"lessThan": "5.1.1",
"versionType": "semver"
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{
"status": "unaffected",
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"published": "2026-09-16T15:18:59.653",
"references": [
{
"url": "https://cna.openjsf.org/security-advisories.html",
"source": "ce714d77-add3-4f53-aff5-83d477b104bb"
},
{
"url": "https://github.com/fastify/fastify-auth/security/advisories/GHSA-7h52-2rwr-m76r",
"source": "ce714d77-add3-4f53-aff5-83d477b104bb"
}
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"vulnStatus": "Awaiting Analysis",
"weaknesses": [
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"description": [
{
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{
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"descriptions": [
{
"lang": "en",
"value": "@fastify/auth is a Fastify plugin that composes multiple authentication and authorization strategies into a single route guard. In versions 5.0.0 through 5.1.0, when strategies are composed with the relation \"or\" option together with the run \"all\" option and one entry is a nested array acting as an AND group, the group is evaluated in an order-dependent way: an earlier failing check is silently dropped and the group's result becomes the outcome of its last check. As a result, a request that satisfies only the last member of an AND group, for example an attacker who holds a valid API key but is not an administrator, is authorized instead of rejected, and a related order-dependent bypass affects the mirror configuration where the top-level relation is \"and\" and a nested group uses \"or\". The issue is fixed in @fastify/auth 5.1.1, and users should upgrade to 5.1.1 or later. As a workaround, omit the run \"all\" option where it is not required, order each AND group so its stricter check is evaluated last, or replace nested AND groups with an explicit top-level \"and\" composition."
}
],
"lastModified": "2026-09-17T20:18:55.393",
"sourceIdentifier": "ce714d77-add3-4f53-aff5-83d477b104bb"
}