FKIE_CVE-2026-21908
Vulnerability from fkie_nvd - Published: 2026-01-15 21:16 - Updated: 2026-01-23 19:40
Severity ?
Summary
A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that could allow an authenticated, network-adjacent attacker flapping a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code within the context of the process running as root.
The issue is specific to the processing of a change in authorization (CoA) when a port bounce occurs. A pointer is freed but was then referenced later in the same code path. Successful exploitation is outside the attacker's direct control due to the specific timing of the two events required to execute the vulnerable code path.
This issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.
This issue affects:
Junos OS:
* from 23.2R2-S1 before 23.2R2-S5,
* from 23.4R2 before 23.4R2-S6,
* from 24.2 before 24.2R2-S3,
* from 24.4 before 24.4R2-S1,
* from 25.2 before 25.2R1-S2, 25.2R2;
Junos OS Evolved:
* from 23.2R2-S1 before 23.2R2-S5-EVO,
* from 23.4R2 before 23.4R2-S6-EVO,
* from 24.2 before 24.2R2-S3-EVO,
* from 24.4 before 24.4R2-S1-EVO,
* from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO.
References
| URL | Tags | ||
|---|---|---|---|
| sirt@juniper.net | https://kb.juniper.net/JSA106007 | Vendor Advisory | |
| sirt@juniper.net | https://supportportal.juniper.net/JSA106007 | Vendor Advisory |
Impacted products
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{
"lang": "en",
"value": "A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of\u00a0Juniper Networks Junos OS and Junos OS Evolved that could allow an authenticated, network-adjacent attacker flapping a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code within the context of the process running as root.\n\nThe issue is specific to the processing of a change in authorization (CoA) when a port bounce occurs. A pointer is freed but was then referenced later in the same code path. Successful exploitation is outside the attacker\u0027s direct control due to the specific timing of the two events required to execute the vulnerable code path.\n\nThis issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.\nThis issue affects:\n\nJunos OS:\u00a0\n\n\n\n * from 23.2R2-S1 before 23.2R2-S5,\u00a0\n * from 23.4R2 before 23.4R2-S6,\u00a0\n * from 24.2 before 24.2R2-S3,\u00a0\n * from 24.4 before 24.4R2-S1,\u00a0\n * from 25.2 before 25.2R1-S2, 25.2R2;\u00a0\n\n\n\n\nJunos OS Evolved:\u00a0\n\n\n\n * from 23.2R2-S1 before 23.2R2-S5-EVO,\u00a0\n * from 23.4R2 before 23.4R2-S6-EVO,\u00a0\n * from 24.2 before 24.2R2-S3-EVO,\u00a0\n * from 24.4 before 24.4R2-S1-EVO,\u00a0\n * from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO."
},
{
"lang": "es",
"value": "Una vulnerabilidad de Use After Free fue identificada en el demonio de autenticaci\u00f3n 802.1X (dot1xd) de Juniper Networks Junos OS y Junos OS Evolved que podr\u00eda permitir a un atacante autenticado y adyacente a la red, alternando un puerto, bloquear el proceso dot1xd, lo que lleva a una denegaci\u00f3n de servicio (DoS), o potencialmente ejecutar c\u00f3digo arbitrario dentro del contexto del proceso que se ejecuta como root.\n\nEl problema es espec\u00edfico del procesamiento de un cambio en la autorizaci\u00f3n (CoA) cuando ocurre un rebote de puerto. Un puntero es liberado pero luego fue referenciado m\u00e1s tarde en la misma ruta de c\u00f3digo. La explotaci\u00f3n exitosa est\u00e1 fuera del control directo del atacante debido a la sincronizaci\u00f3n espec\u00edfica de los dos eventos requeridos para ejecutar la ruta de c\u00f3digo vulnerable.\n\nEste problema afecta a sistemas con autenticaci\u00f3n 802.1X con control de acceso a la red basado en puerto (PNAC) habilitado.\nEste problema afecta a:\n\nJunos OS:\n\n * desde 23.2R2-S1 antes de 23.2R2-S5,\n * desde 23.4R2 antes de 23.4R2-S6,\n * desde 24.2 antes de 24.2R2-S3,\n * desde 24.4 antes de 24.4R2-S1,\n * desde 25.2 antes de 25.2R1-S2, 25.2R2;\n\nJunos OS Evolved:\n\n * desde 23.2R2-S1 antes de 23.2R2-S5-EVO,\n * desde 23.4R2 antes de 23.4R2-S6-EVO,\n * desde 24.2 antes de 24.2R2-S3-EVO,\n * desde 24.4 antes de 24.4R2-S1-EVO,\n * desde 25.2 antes de 25.2R1-S2-EVO, 25.2R2-EVO."
}
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"id": "CVE-2026-21908",
"lastModified": "2026-01-23T19:40:42.420",
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"attackVector": "ADJACENT_NETWORK",
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"baseScore": 7.1,
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"scope": "UNCHANGED",
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"confidentialityRequirement": "NOT_DEFINED",
"exploitMaturity": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
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"published": "2026-01-15T21:16:06.537",
"references": [
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"tags": [
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"url": "https://kb.juniper.net/JSA106007"
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"value": "CWE-416"
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"type": "Primary"
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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