CVE-2026-89420
Improper Validation of Specified Quantity in Input in ZenHive mpp allows a client holding an open payment channel to obtain paid resources without being charged.
MPP.Session.Actions.accept_voucher/3 in lib/mpp/session/actions.ex treats a voucher whose cumulativeAmount equals the channel's already-accepted cumulative amount as an idempotent success, returning the channel unchanged without calling maybe_spend/2. The credential verifies, the protected resource is served, and spent and units stay where they were.
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Because the server issues a fresh challenge per request and the credential replay store keys on challenge id and payload, the same signed voucher can be re-presented under every new challenge, so one paid voucher yields an unbounded number of paid units. The path is reachable from any method built on MPP.Session.Method through the Plug, MCP, JSON-RPC and WebSocket transports.
This issue affects mpp: from 0.14.0 before 0.16.2.
CVSS
- Versión: 4.0
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/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: 7.1
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.41%
- Percentil entre todas las CVEs puntuadas: 33
- Fecha de la puntuación: 5/10/2026
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
T1578Modify Cloud Compute Infrastructuredefense impairment70 % - Impacto secundario
T1005Data from Local Systemcollection65 %
AV:N con PR:L permite explotación remota en servicios. Reutilización de voucher firmado sin validación de cantidad permite acceso repetido a recursos pagos sin cargo (fraude de acceso/manipulación de recursos).
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-1284
Referencias
- https://cna.erlef.org/cves/CVE-2026-89420.html
- https://github.com/ZenHive/mpp/commit/7270edc1dcfb58250cc5ee812876609206564165
- https://github.com/ZenHive/mpp/commit/82df569c898be1137189e3648e1edb4af6363651
- https://github.com/ZenHive/mpp/security/advisories/GHSA-8c63-r789-xrrf
- https://osv.dev/vulnerability/EEF-CVE-2026-89420
- https://github.com/ZenHive/mpp/security/advisories/GHSA-8c63-r789-xrrf
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-89420",
"cveTags": [],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-89420",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "poc"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"version": "2.0.3",
"timestamp": "2026-09-22T12:03:58.968313Z"
}
}
],
"cvssMetricV40": [
{
"type": "Secondary",
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"cvssData": {
"Safety": "NOT_DEFINED",
"version": "4.0",
"Recovery": "NOT_DEFINED",
"baseScore": 7.1,
"Automatable": "NOT_DEFINED",
"attackVector": "NETWORK",
"baseSeverity": "HIGH",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/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",
"privilegesRequired": "LOW",
"subIntegrityImpact": "NONE",
"vulnIntegrityImpact": "HIGH",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"vulnAvailabilityImpact": "NONE",
"availabilityRequirement": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"subConfidentialityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"confidentialityRequirement": "NOT_DEFINED",
"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"
}
}
]
},
"affected": [
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"affectedData": [
{
"cpes": [
"cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"
],
"repo": "https://github.com/ZenHive/mpp",
"vendor": "ZenHive",
"modules": [
"'Elixir.MPP.Session.Actions'"
],
"product": "mpp",
"versions": [
{
"status": "affected",
"version": "0.14.0",
"lessThan": "0.16.2",
"versionType": "semver"
}
],
"packageURL": "pkg:hex/mpp",
"packageName": "mpp",
"programFiles": [
"lib/mpp/session/actions.ex"
],
"collectionURL": "https://repo.hex.pm",
"defaultStatus": "unaffected",
"programRoutines": [
{
"name": "'Elixir.MPP.Session.Actions':dispatch/2"
},
{
"name": "'Elixir.MPP.Session.Actions':handle/2"
}
]
},
{
"cpes": [
"cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"
],
"repo": "https://github.com/ZenHive/mpp",
"vendor": "ZenHive",
"modules": [
"'Elixir.MPP.Session.Actions'"
],
"product": "mpp",
"versions": [
{
"status": "affected",
"version": "82df569c898be1137189e3648e1edb4af6363651",
"lessThan": "7270edc1dcfb58250cc5ee812876609206564165",
"versionType": "git"
}
],
"packageURL": "pkg:github/zenhive/mpp",
"packageName": "zenhive/mpp",
"programFiles": [
"lib/mpp/session/actions.ex"
],
"collectionURL": "https://github.com",
"defaultStatus": "unaffected",
"programRoutines": [
{
"name": "'Elixir.MPP.Session.Actions':dispatch/2"
},
{
"name": "'Elixir.MPP.Session.Actions':handle/2"
}
]
}
]
}
],
"published": "2026-09-22T12:17:14.370",
"references": [
{
"url": "https://cna.erlef.org/cves/CVE-2026-89420.html",
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
},
{
"url": "https://github.com/ZenHive/mpp/commit/7270edc1dcfb58250cc5ee812876609206564165",
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
},
{
"url": "https://github.com/ZenHive/mpp/commit/82df569c898be1137189e3648e1edb4af6363651",
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
},
{
"url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-8c63-r789-xrrf",
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
},
{
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-89420",
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
},
{
"url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-8c63-r789-xrrf",
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
}
],
"vulnStatus": "Deferred",
"weaknesses": [
{
"type": "Secondary",
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"description": [
{
"lang": "en",
"value": "CWE-1284"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Improper Validation of Specified Quantity in Input in ZenHive mpp allows a client holding an open payment channel to obtain paid resources without being charged.\n\nMPP.Session.Actions.accept_voucher/3 in lib/mpp/session/actions.ex treats a voucher whose cumulativeAmount equals the channel's already-accepted cumulative amount as an idempotent success, returning the channel unchanged without calling maybe_spend/2. The credential verifies, the protected resource is served, and spent and units stay where they were. Because the server issues a fresh challenge per request and the credential replay store keys on challenge id and payload, the same signed voucher can be re-presented under every new challenge, so one paid voucher yields an unbounded number of paid units. The path is reachable from any method built on MPP.Session.Method through the Plug, MCP, JSON-RPC and WebSocket transports.\n\nThis issue affects mpp: from 0.14.0 before 0.16.2."
}
],
"lastModified": "2026-09-22T19:09:32.273",
"sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}