CVE-2026-21921
Estado: AnalizadaAlta (7.1)—
A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS).
When telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered.
This issue affects:
Junos OS:
Junos OS Evolved:
Detalles técnicos trazas, registros y código del informe original
* all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S5, * 23.4 versions before 23.4R2; * all versions before 22.4R3-S8-EVO, * 23.2 versions before 23.2R2-S5-EVO, * 23.4 versions before 23.4R2-EVO.
CVSS
- Versión: 4.0
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/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:Y/R:A/V:X/RE:M/U:X
- Puntuación base: 7.1
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.38%
- Percentil entre todas las CVEs puntuadas: 30
- 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
T1210Exploitation of Remote Serviceslateral movement85 % - Impacto principal
T1499.004Application or System Exploitationimpact90 %
Vulnerabilidad de Use After Free (CWE-416) en daemon remoto que requiere autenticación de bajo nivel (PR:L). Ataque de red autenticado causa crash reiterado de procesos críticos (chassisd, rpd, mib2d) y desconexión completa del sistema, encajando con negación de servicio por degradación 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 (2)
CWE
- CWE-416
Referencias
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-21921",
"cveTags": [],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-21921",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"version": "2.0.3",
"timestamp": "2026-01-15T20:54:58.001808Z"
}
}
],
"cvssMetricV31": [
{
"type": "Secondary",
"source": "sirt@juniper.net",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 6.5,
"attackVector": "NETWORK",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "NONE"
},
"impactScore": 3.6,
"exploitabilityScore": 2.8
}
],
"cvssMetricV40": [
{
"type": "Secondary",
"source": "sirt@juniper.net",
"cvssData": {
"Safety": "NOT_DEFINED",
"version": "4.0",
"Recovery": "AUTOMATIC",
"baseScore": 7.1,
"Automatable": "YES",
"attackVector": "NETWORK",
"baseSeverity": "HIGH",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/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:Y/R:A/V:X/RE:M/U:X",
"exploitMaturity": "NOT_DEFINED",
"providerUrgency": "NOT_DEFINED",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"privilegesRequired": "LOW",
"subIntegrityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"subAvailabilityImpact": "LOW",
"vulnAvailabilityImpact": "HIGH",
"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": "MODERATE",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED"
}
}
]
},
"affected": [
{
"source": "sirt@juniper.net",
"affectedData": [
{
"vendor": "Juniper Networks",
"product": "Junos OS",
"versions": [
{
"status": "affected",
"version": "0",
"lessThan": "22.4R3-S8",
"versionType": "semver"
},
{
"status": "affected",
"version": "23.2",
"lessThan": "23.2R2-S5",
"versionType": "semver"
},
{
"status": "affected",
"version": "23.4",
"lessThan": "23.4R2",
"versionType": "semver"
}
],
"defaultStatus": "unaffected"
},
{
"vendor": "Juniper Networks",
"product": "Junos OS Evolved",
"versions": [
{
"status": "affected",
"version": "0",
"lessThan": "22.4R3-S8-EVO",
"versionType": "semver"
},
{
"status": "affected",
"version": "23.2",
"lessThan": "23.2R2-S5-EVO",
"versionType": "semver"
},
{
"status": "affected",
"version": "23.4",
"lessThan": "23.4R2-EVO",
"versionType": "semver"
}
],
"defaultStatus": "unaffected"
}
]
}
],
"published": "2026-01-15T21:16:08.400",
"references": [
{
"url": "https://kb.juniper.net/JSA106021",
"tags": [
"Vendor Advisory"
],
"source": "sirt@juniper.net"
},
{
"url": "https://supportportal.juniper.net/JSA106021",
"tags": [
"Vendor Advisory"
],
"source": "sirt@juniper.net"
}
],
"vulnStatus": "Analyzed",
"weaknesses": [
{
"type": "Secondary",
"source": "sirt@juniper.net",
"description": [
{
"lang": "en",
"value": "CWE-416"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS).\n\nWhen telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered.\n\nThis issue affects:\n\n Junos OS: \n\n\n\n * all versions before 22.4R3-S8,\n * 23.2 versions before 23.2R2-S5,\n * 23.4 versions before 23.4R2;\n\n\n\n\nJunos OS Evolved:\n\n\n\n * all versions before 22.4R3-S8-EVO,\n * 23.2 versions before 23.2R2-S5-EVO,\n * 23.4 versions before 23.4R2-EVO."
},
{
"lang": "es",
"value": "Una vulnerabilidad de Uso Después de Liberar en el demonio de chasis (chassisd) de Juniper Networks Junos OS y Junos OS Evolved permite a un atacante basado en red autenticado con bajos privilegios causar una Denegación de Servicio (DoS).\n\nCuando los recolectores de telemetría se suscriben y anulan la suscripción a sensores frecuentemente y de forma continua durante un largo período de tiempo, los procesos con capacidad de telemetría como chassisd, rpd o mib2d se bloquearán y reiniciarán, lo cual - dependiendo del proceso - puede causar una interrupción completa hasta que el sistema se haya recuperado.\n\nEste problema afecta:\n\nJunos OS:\n\n * todas las versiones anteriores a 22.4R3-S8,\n * versiones 23.2 anteriores a 23.2R2-S5,\n * versiones 23.4 anteriores a 23.4R2;\n\nJunos OS Evolved:\n\n * todas las versiones anteriores a 22.4R3-S8-EVO,\n * versiones 23.2 anteriores a 23.2R2-S5-EVO,\n * versiones 23.4 anteriores a 23.4R2-EVO."
}
],
"lastModified": "2026-06-17T10:19:10.153",
"configurations": [
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "57F66641-003B-49D6-A9B9-AB300CFE3C93",
"versionEndExcluding": "22.4"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:-:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "1379EF30-AF04-4F98-8328-52A631F24737"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "28E42A41-7965-456B-B0AF-9D3229CE4D4C"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r1-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "CB1A77D6-D3AD-481B-979C-8F778530B175"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r1-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "3A064B6B-A99B-4D8D-A62D-B00C7870BC30"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "40813417-A938-4F74-A419-8C5188A35486"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r2-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "7FC1BA1A-DF0E-4B15-86BA-24C60E546732"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r2-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "EBB967BF-3495-476D-839A-9DBFCBE69F91"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r3:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "7E5688D6-DCA4-4550-9CD1-A3D792252129"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r3-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "8494546C-00EA-49B6-B6FA-FDE42CA5B1FA"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r3-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "8BB98579-FA33-4E41-A162-A46E9709FBD3"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r3-s3:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "08E2562F-FB18-4347-8497-7D61B8157EBB"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r3-s4:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "494D1D96-1DA2-4B0A-9536-1B5A4FDFCA09"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r3-s5:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "60A1E37B-1990-44D9-87FE-300678243BE2"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r3-s6:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "D306ED88-8700-4FD4-8919-3C85728C04C3"
},
{
"criteria": "cpe:2.3:o:juniper:junos:22.4:r3-s7:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "11340C63-A638-420C-85C9-1B4438C88D52"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.2:-:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "1A78CC80-E8B1-4CDA-BB35-A61833657FA7"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "4B3B2FE1-C228-46BE-AC76-70C2687050AE"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "F1B16FF0-900F-4AEE-B670-A537139F6909"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "B227E831-30FF-4BE1-B8B2-31829A5610A6"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.2:r2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "1ADA814B-EF98-45B1-AF7A-0C89688F7CA5"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.2:r2-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "A6FB32DF-D062-4FB9-8777-452978BEC7B7"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.2:r2-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "B3B6C811-5C10-4486-849D-5559B592350A"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.2:r2-s3:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "078D61B9-A228-453C-9D20-6F9C6B20637F"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.2:r2-s4:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "F1F136A0-021D-43FE-BDD3-AD7201F7FC03"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "78481ABC-3620-410D-BC78-334657E0BB75"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "BE8A5BA3-87BD-473A-B229-2AAB2C797005"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "8B74AC3E-8FC9-400A-A176-4F7F21F10756"
},
{
"criteria": "cpe:2.3:o:juniper:junos:23.4:r1-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "CB2D1FCE-8019-4CE1-BA45-D62F91AF7B51"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "A9925263-E7B7-49AA-8271-AF320F355B80",
"versionEndExcluding": "22.4"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:-:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "0A33C425-921F-4795-B834-608C8F1597E0"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "93887799-F62C-4A4A-BCF5-004D0B4D4154"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r1-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "62C473D2-2612-4480-82D8-8A24D0687BBD"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r1-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "7FB4C5CA-A709-4B13-A9E0-372098A72AD3"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "04CE952D-E3C1-4B34-9E65-EC52BFE887AB"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r2-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "8AE9D1A7-4721-4E1D-B965-FDC38126B1DD"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r2-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "A8643AA3-29EF-48A7-B033-CB60988E214B"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r3:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "9800BA03-E6BF-4212-B2E7-69C0FD27D294"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "ACCA655D-C542-44F1-B183-4C864CFF2D4F"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "6D499B19-A91A-4B76-B1CB-6A07A4CB212B"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s3:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "B6B2830C-26EE-446E-B0C3-B5E43AD897B8"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s4:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "1C7367E6-B491-4A1F-B9D7-BC86A15A0773"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s5:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "72A89D1E-9EA4-4959-9F54-84F1F99A4ADB"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s6:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "01980CDF-A5CE-480D-BCED-BD5E29E4DE5F"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:22.4:r3-s7:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "BA6ECC3B-657C-4475-95B0-1FD18B076BC5"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.2:-:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "6DEAA7FD-385F-4221-907E-65ABC16BE4BE"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.2:r1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "DDEC008A-3137-48D1-8ABC-6DB0EFC40E50"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.2:r1-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "558D234D-BC50-415F-86D6-8E19D6C3ACE0"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.2:r1-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "33F4EEEE-77E9-4973-A770-99E7BA2F05F5"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.2:r2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "A4BB6910-B994-45FD-8153-5EC00EE842E6"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "D657944B-2066-4F2C-BC92-EDF4DE1C165C"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "75A58924-6348-44CF-AB39-1FCE17FE81AC"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s3:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "9A903B31-D9E5-43FA-B09F-7E7769803720"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.2:r2-s4:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "E23BEA27-77F8-4CDF-A49A-FEF9C33DA513"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.4:-:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "9D7F0D73-85EE-4A07-B51B-6BF52ECBA75E"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.4:r1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "FE777A1F-9CD9-426E-AF1C-FBE01EB9A4A8"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.4:r1-s1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "7147BA60-30A5-4CED-9AAF-F6BEA0528B89"
},
{
"criteria": "cpe:2.3:o:juniper:junos_os_evolved:23.4:r1-s2:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "6E5CE59B-14B2-4F4C-81B5-0430EC954956"
}
],
"operator": "OR"
}
]
}
],
"sourceIdentifier": "sirt@juniper.net"
}