CVE-2026-5749
Inadequate access control in the registration process in Fullstep V5, which could allow unauthenticated users to obtain a valid JWT token with which to interact with authenticated API resources. Successful exploitation of this vulnerability could allow an unauthenticated attacker to compromise the confidentiality of the affected resource, provided they have a valid token with which to interact with the API.
CVSS
- Versión: 4.0
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Puntuación base: 8.7
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.42%
- Percentil entre todas las CVEs puntuadas: 34
- Fecha de la puntuación: 4/10/2026
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 access85 % - Impacto principal
T1078Valid Accountsstealth · persistence · privilege escalation · initial access90 % - Impacto secundario
T1005Data from Local Systemcollection75 %
Acceso a red sin autenticación (AV:N, PR:N, UI:N) permite obtener JWT válidos para acceder a recursos autenticados (T1078). CWE-306 (falta de control de acceso) en registro de Fullstep V5 expone datos confidenciales (VC:H).
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-306
Referencias
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-5749",
"cveTags": [],
"metrics": {
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{
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"ssvcData": {
"id": "CVE-2026-5749",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "none"
},
{
"automatable": "yes"
},
{
"technicalImpact": "partial"
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],
"version": "2.0.3",
"timestamp": "2026-04-22T14:02:34.571025Z"
}
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"cvssMetricV40": [
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"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"exploitMaturity": "NOT_DEFINED",
"providerUrgency": "NOT_DEFINED",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
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"subIntegrityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"vulnAvailabilityImpact": "NONE",
"availabilityRequirement": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"subConfidentialityImpact": "NONE",
"vulnConfidentialityImpact": "HIGH",
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"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"vulnerabilityResponseEffort": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED"
}
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},
"affected": [
{
"source": "cve-coordination@incibe.es",
"affectedData": [
{
"vendor": "Fullstep",
"product": "Fullstep",
"versions": [
{
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"version": "5"
},
{
"status": "unaffected",
"version": "5.30.07"
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],
"published": "2026-04-22T14:17:05.993",
"references": [
{
"url": "https://www.incibe.es/en/incibe-cert/notices/aviso/multiple-vulnerabilities-fullstep",
"source": "cve-coordination@incibe.es"
}
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"vulnStatus": "Deferred",
"weaknesses": [
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"type": "Secondary",
"source": "cve-coordination@incibe.es",
"description": [
{
"lang": "en",
"value": "CWE-306"
}
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"descriptions": [
{
"lang": "en",
"value": "Inadequate access control in the registration process in Fullstep V5, which could allow unauthenticated users to obtain a valid JWT token with which to interact with authenticated API resources. Successful exploitation of this vulnerability could allow an unauthenticated attacker to compromise the confidentiality of the affected resource, provided they have a valid token with which to interact with the API."
}
],
"lastModified": "2026-06-17T10:59:35.707",
"sourceIdentifier": "cve-coordination@incibe.es"
}