{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2021-0254",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-0254",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2021-04-22T19:37:15.413Z",
    "updatedAt": "2024-09-16T20:11:30.725Z",
    "importedAt": "2026-10-24T01:56:21.187Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "Junos OS: Remote code execution vulnerability in overlayd service",
      "summary": "A buffer size validation vulnerability in the overlayd service of Juniper Networks Junos OS may allow an unauthenticated remote attacker to send specially crafted packets to the device, triggering a partial Denial of Service (DoS) condition, or leading to remote code execution (RCE). Continued receipt and processing of these packets will sustain the partial DoS. The overlayd daemon handles Overlay OAM packets, such as ping and traceroute, sent to the overlay. The service runs as root by default and listens for UDP connections on port 4789. This issue results from improper buffer size validation, which can lead to a buffer overflow. Unauthenticated attackers can send specially crafted packets to trigger this vulnerability, resulting in possible remote code execution. overlayd runs by default in MX Series, ACX Series, and QFX Series platforms. The SRX Series does not support VXLAN and is therefore not vulnerable to this issue. Other platforms are also vulnerable if a Virtual Extensible LAN (VXLAN) overlay network is configured. This issue affects Juniper Networks Junos OS: 15.1 versions prior to 15.1R7-S9; 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S13, 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R2-S8, 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R1-S8, 18.4R2-S7, 18.4R3-S7; 19.1 versions prior to 19.1R2-S2, 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R2-S4, 19.4R3-S1; 20.1 versions prior to 20.1R2-S1, 20.1R3; 20.2 versions prior to 20.2R2, 20.2R2-S1, 20.2R3; 20.3 versions prior to 20.3R1-S1.",
      "affected": [
        {
          "vendor": "Juniper Networks",
          "product": "Junos OS",
          "versions": [
            {
              "version": "15.1",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "15.1R7-S9"
            },
            {
              "version": "17.3",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "17.3R3-S11"
            },
            {
              "version": "17.4",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "17.4R2-S13, 17.4R3-S4"
            },
            {
              "version": "18.1",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "18.1R3-S12"
            },
            {
              "version": "18.2",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "18.2R2-S8, 18.2R3-S7"
            },
            {
              "version": "18.3",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "18.3R3-S4"
            },
            {
              "version": "18.4",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "18.4R1-S8, 18.4R2-S7, 18.4R3-S7"
            },
            {
              "version": "19.1",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "19.1R2-S2, 19.1R3-S4"
            },
            {
              "version": "19.2",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "19.2R1-S6, 19.2R3-S2"
            },
            {
              "version": "19.3",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "19.3R3-S1"
            },
            {
              "version": "19.4",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "19.4R2-S4, 19.4R3-S1"
            },
            {
              "version": "20.1",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "20.1R2-S1, 20.1R3"
            },
            {
              "version": "20.2",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "20.2R2, 20.2R2-S1, 20.2R3"
            },
            {
              "version": "20.3",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "20.3R1-S1"
            }
          ]
        }
      ]
    }
  }
}