Vulnerability-Lookup

FKIE_CVE-2021-0239

Vulnerability from fkie_nvd - Published: 2021-04-22 20:15 - Updated: 2026-06-17 03:29

Severity

6.5 (Medium) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.5 (Medium) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

In Juniper Networks Junos OS Evolved, receipt of a stream of specific genuine Layer 2 frames may cause the Advanced Forwarding Toolkit (AFT) manager process (Evo-aftmand), responsible for handling Route, Class-of-Service (CoS), Firewall operations within the packet forwarding engine (PFE) to crash and restart, leading to a Denial of Service (DoS) condition. By continuously sending this specific stream of genuine Layer 2 frames, an attacker can repeatedly crash the PFE, causing a sustained Denial of Service (DoS). This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R1-EVO. This issue does not affect Junos OS versions.

References

	URL	Tags
	sirt@juniper.net	https://kb.juniper.net/JSA11134	Vendor Advisory
	af854a3a-2127-422b-91ae-364da2661108	https://kb.juniper.net/JSA11134	Vendor Advisory

Impacted products

	Vendor	Product	Version
	juniper	junos_os_evolved	20.4

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "Junos OS Evolved",
          "vendor": "Juniper Networks",
          "versions": [
            {
              "lessThan": "20.4R1-EVO",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "sirt@juniper.net"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:juniper:junos_os_evolved:20.4:r1:*:*:*:*:*:*",
              "matchCriteriaId": "C9C8866D-162F-4C9B-8167-2FBA25410368",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In Juniper Networks Junos OS Evolved, receipt of a stream of specific genuine Layer 2 frames may cause the Advanced Forwarding Toolkit (AFT) manager process (Evo-aftmand), responsible for handling Route, Class-of-Service (CoS), Firewall operations within the packet forwarding engine (PFE) to crash and restart, leading to a Denial of Service (DoS) condition. By continuously sending this specific stream of genuine Layer 2 frames, an attacker can repeatedly crash the PFE, causing a sustained Denial of Service (DoS). This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R1-EVO. This issue does not affect Junos OS versions."
    },
    {
      "lang": "es",
      "value": "En Juniper Networks, Junos OS Evolved, la recepci\u00f3n de un flujo de tramas de capa 2 genuinas espec\u00edficas puede causar que el proceso de gesti\u00f3n Advanced Forwarding Toolkit (AFT) (Evo-aftmand), responsable de gestionar las operaciones de ruta, clase de servicio (CoS) y cortafuegos. dentro del packet forwarding engine (PFE) para bloquearse y reiniciarse, conllevando a una condici\u00f3n de Denegaci\u00f3n de Servicio (DoS).\u0026#xa0;Al enviar continuamente este flujo espec\u00edfico de tramas genuinas de Capa 2, Un atacante puede ser capaz de bloquear repetidamente el PFE, provocando una Denegaci\u00f3n de Servicio (DoS) sostenida.\u0026#xa0;Este problema afecta a Juniper Networks Junos OS Evolved: todas las versiones anteriores a 20.4R1-EVO.\u0026#xa0;Este problema no afecta a Junos OS versiones"
    }
  ],
  "id": "CVE-2021-0239",
  "lastModified": "2026-06-17T03:29:34.513",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "LOW",
          "accessVector": "ADJACENT_NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "COMPLETE",
          "baseScore": 6.1,
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "vectorString": "AV:A/AC:L/Au:N/C:N/I:N/A:C",
          "version": "2.0"
        },
        "exploitabilityScore": 6.5,
        "impactScore": 6.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.6,
        "source": "sirt@juniper.net",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-04-22T20:15:08.943",
  "references": [
    {
      "source": "sirt@juniper.net",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://kb.juniper.net/JSA11134"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://kb.juniper.net/JSA11134"
    }
  ],
  "sourceIdentifier": "sirt@juniper.net",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-754"
        }
      ],
      "source": "sirt@juniper.net",
      "type": "Secondary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-754"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2021-0239 (GCVE-0-2021-0239)

Vulnerability from cvelistv5 – Published: 2021-04-22 19:37 – Updated: 2024-09-16 17:49

Title

Junos OS Evolved: Denial of Service due to receipt of specific genuine layer 2 frames.

Summary

Severity

6.5 (Medium)


                        
                          CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE

CWE-754 - Improper Check for Unusual or Exceptional Conditions
Denial of Service (DoS)

Assigner

juniper mitre root Scorecard

References

1 reference

URL	Tags
https://kb.juniper.net/JSA11134	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
Juniper Networks	Junos OS Evolved	Affected: unspecified , < 20.4R1-EVO (custom)

Date Public

2021-04-14 00:00

Show details on NVD website

JSON

To clipboard

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          "dateUpdated": "2024-08-03T15:32:09.949Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
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        "references": [
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              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://kb.juniper.net/JSA11134"
          }
        ],
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    ],
    "cna": {
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          "vendor": "Juniper Networks",
          "versions": [
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              "version": "unspecified",
              "versionType": "custom"
            }
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        }
      ],
      "datePublic": "2021-04-14T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "In Juniper Networks Junos OS Evolved, receipt of a stream of specific genuine Layer 2 frames may cause the Advanced Forwarding Toolkit (AFT) manager process (Evo-aftmand), responsible for handling Route, Class-of-Service (CoS), Firewall operations within the packet forwarding engine (PFE) to crash and restart, leading to a Denial of Service (DoS) condition. By continuously sending this specific stream of genuine Layer 2 frames, an attacker can repeatedly crash the PFE, causing a sustained Denial of Service (DoS). This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R1-EVO. This issue does not affect Junos OS versions."
        }
      ],
      "exploits": [
        {
          "lang": "en",
          "value": "Juniper SIRT is not aware of any malicious exploitation of this vulnerability."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "ADJACENT_NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
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      "problemTypes": [
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          ],
          "url": "https://kb.juniper.net/JSA11134"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "The following software releases have been updated to resolve this specific issue: Junos OS Evolved: 20.4R1-EVO, and all subsequent releases."
        }
      ],
      "source": {
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        "defect": [
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        ],
        "discovery": "INTERNAL"
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      "workarounds": [
        {
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          "value": "There are no viable workarounds for this issue."
        }
      ],
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      "x_legacyV4Record": {
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          "DATE_PUBLIC": "2021-04-14T16:00:00.000Z",
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          "STATE": "PUBLIC",
          "TITLE": "Junos OS Evolved: Denial of Service due to receipt of specific genuine layer 2 frames."
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        "affects": {
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            "vendor_data": [
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}

Sightings

Author	Source	Type	Date	Other

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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FKIE_CVE-2021-0239

CVE-2021-0239 (GCVE-0-2021-0239)

Tags

Sightings

Nomenclature

Related by attack behaviour