FKIE_CVE-2026-21901

Vulnerability from fkie_nvd - Published: 2026-07-09 21:16 - Updated: 2026-07-09 21:16
Severity
4.4 (Medium) - CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Summary
A NULL Pointer Dereference vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a local, high-privileged attacker setting or deactivating a specific SSH configuration parameter to create a Denial of Service (DoS). A local high-privileged user configuring or deactivating a specific 'system services ssh' configuration parameter can exploit a null pointer dereference in one of the functions used by SSH. The function attempts to dereference a null pointer when accessing certain configuration data, resulting in an mgd process crash and restart. Continued execution of these configuration commands will create a sustained Denial of Service (DoS) condition. This issue affects: Junos OS: * from 22.3 before 22.3R3-S5; * from 22.4 before 22.4R3-S10; * from 23.2 before 23.2R2-S7; * from 23.4 before 23.4R2-S8. This issue does not affect Junos OS before 22.3R1. Junos OS Evolved: * from 22.3R1-EVO before 23.2R2-S7-EVO; * from 23.4 before 23.4R2-S8-EVO. This issue does not affect Junos OS Evolved before 22.3R1-EVO.
References
sirt@juniper.nethttps://github.com/orangecertcc/security-research/security/advisories/GHSA-g4f7-w2rc-hpj6
sirt@juniper.nethttps://supportportal.juniper.net/JSA110072
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Junos OS",
          "vendor": "Juniper Networks",
          "versions": [
            {
              "lessThan": "22.3R3-S5",
              "status": "affected",
              "version": "22.3",
              "versionType": "custom"
            },
            {
              "lessThan": "22.4R3-S10",
              "status": "affected",
              "version": "22.4",
              "versionType": "custom"
            },
            {
              "lessThan": "23.2R2-S7",
              "status": "affected",
              "version": "23.2",
              "versionType": "custom"
            },
            {
              "lessThan": "23.4R2-S8",
              "status": "affected",
              "version": "23.4",
              "versionType": "custom"
            },
            {
              "lessThan": "22.3R1",
              "status": "unaffected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "Junos OS Evolved",
          "vendor": "Juniper Networks",
          "versions": [
            {
              "lessThan": "23.2R2-S7-EVO",
              "status": "affected",
              "version": "23.2",
              "versionType": "custom"
            },
            {
              "lessThan": "23.4R2-S8-EVO",
              "status": "affected",
              "version": "23.4",
              "versionType": "custom"
            },
            {
              "lessThan": "22.3R1-EVO",
              "status": "unaffected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "sirt@juniper.net"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A NULL Pointer Dereference vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a local, high-privileged attacker setting or deactivating a\u00a0specific SSH configuration parameter to create a Denial of Service (DoS).\n\nA local high-privileged user configuring or deactivating a specific \u0027system services ssh\u0027 configuration parameter\u00a0can exploit a null pointer dereference in one of the functions used by SSH. The function attempts to dereference a null pointer when accessing certain configuration data, resulting in an mgd process crash and restart.\u00a0Continued execution of these configuration commands will create a sustained Denial of Service (DoS) condition.\n\nThis issue affects:\nJunos OS:\n\n\n  *  from 22.3 before 22.3R3-S5;\n  *  from 22.4 before 22.4R3-S10;\n  *  from 23.2 before 23.2R2-S7;\n  *  from 23.4 before 23.4R2-S8.\n\n\n\n\nThis issue does not affect Junos OS before 22.3R1.\n\n\n\nJunos OS Evolved:\n  *  from 22.3R1-EVO before 23.2R2-S7-EVO;\n  *  from 23.4 before 23.4R2-S8-EVO.\n\n\nThis issue does not affect Junos OS Evolved before 22.3R1-EVO."
    }
  ],
  "id": "CVE-2026-21901",
  "lastModified": "2026-07-09T21:16:54.467",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 4.4,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "HIGH",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 0.8,
        "impactScore": 3.6,
        "source": "sirt@juniper.net",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "YES",
          "Recovery": "AUTOMATIC",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "LOCAL",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.7,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "HIGH",
          "providerUrgency": "GREEN",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "DIFFUSE",
          "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/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:Y/R:A/V:D/RE:M/U:Green",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "MODERATE"
        },
        "source": "sirt@juniper.net",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-09T21:16:54.467",
  "references": [
    {
      "source": "sirt@juniper.net",
      "url": "https://github.com/orangecertcc/security-research/security/advisories/GHSA-g4f7-w2rc-hpj6"
    },
    {
      "source": "sirt@juniper.net",
      "url": "https://supportportal.juniper.net/JSA110072"
    }
  ],
  "sourceIdentifier": "sirt@juniper.net",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ],
      "source": "sirt@juniper.net",
      "type": "Primary"
    }
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


Detection rules are retrieved from Rulezet.