CVE-2021-3422

Status: ModifiedHigh (7.5)—

The lack of validation of a key-value field in the Splunk-to-Splunk protocol results in a denial-of-service in Splunk Enterprise instances configured to index Universal Forwarder traffic. The vulnerability impacts Splunk Enterprise versions before 7.3.9, 8.0 versions before 8.0.9, and 8.1 versions before 8.1.3. It does not impact Universal Forwarders. When Splunk forwarding is secured using TLS or a Token, the attack requires compromising the certificate or token, or both. Implementation of either or both reduces the severity to Medium.

CVSS

Version: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base score: 7.5

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.60%
Percentile among all scored CVEs: 47
Score date: 10/7/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

Splunk — Splunk

CWEs

CWE-125
CWE-20

References

Raw JSON (NVD)

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{
  "id": "CVE-2021-3422",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
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          "baseScore": 4.3,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:M/Au:N/C:N/I:N/A:P",
          "authentication": "NONE",
          "integrityImpact": "NONE",
          "accessComplexity": "MEDIUM",
          "availabilityImpact": "PARTIAL",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 8.6,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
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    "cvssMetricV31": [
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        "type": "Secondary",
        "source": "prodsec@splunk.com",
        "cvssData": {
          "scope": "UNCHANGED",
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          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
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        "cvssData": {
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  "affected": [
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          "vendor": "Splunk",
          "product": "Splunk Enterprise",
          "versions": [
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              "version": "8.2 version(s) before 8.2.0"
            },
            {
              "status": "affected",
              "version": "8.1 version(s) before 8.1.3"
            },
            {
              "status": "affected",
              "version": "8.0 version(s) before 8.0.9"
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            {
              "status": "affected",
              "version": "7.3 version(s) before 7.3.9"
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  ],
  "published": "2022-03-25T19:15:08.983",
  "references": [
    {
      "url": "https://claroty.com/2022/03/24/blog-research-locking-down-splunk-enterprise-indexers-and-forwarders/",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "prodsec@splunk.com"
    },
    {
      "url": "https://www.splunk.com/en_us/product-security/announcements/svd-2022-0301.html",
      "tags": [
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      "source": "prodsec@splunk.com"
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      "url": "https://claroty.com/2022/03/24/blog-research-locking-down-splunk-enterprise-indexers-and-forwarders/",
      "tags": [
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.splunk.com/en_us/product-security/announcements/svd-2022-0301.html",
      "tags": [
        "Vendor Advisory"
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
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  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "prodsec@splunk.com",
      "description": [
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          "lang": "en",
          "value": "CWE-125"
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    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
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          "value": "CWE-20"
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  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "The lack of validation of a key-value field in the Splunk-to-Splunk protocol results in a denial-of-service in Splunk Enterprise instances configured to index Universal Forwarder traffic. The vulnerability impacts Splunk Enterprise versions before 7.3.9, 8.0 versions before 8.0.9, and 8.1 versions before 8.1.3. It does not impact Universal Forwarders. When Splunk forwarding is secured using TLS or a Token, the attack requires compromising the certificate or token, or both. Implementation of either or both reduces the severity to Medium."
    },
    {
      "lang": "es",
      "value": "La falta de validación de un campo clave-valor en el protocolo Splunk-to-Splunk resulta en una denegación de servicio en las instancias de Splunk Enterprise configuradas para indexar el tráfico de Universal Forwarder. La vulnerabilidad afecta a las versiones de Splunk Enterprise anteriores a la 7.3.9, a las versiones 8.0 anteriores a la 8.0.9 y a las versiones 8.1 anteriores a la 8.1.3. No afecta a los Universal Forwarders. Cuando el reenvío de Splunk está asegurado usando TLS o un Token, el ataque requiere comprometer el certificado o el token, o ambos. La implementación de uno o ambos reduce la severidad a Media"
    }
  ],
  "lastModified": "2026-06-17T04:05:03.630",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "versionEndExcluding": "7.3.9"
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          "operator": "OR"
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  "sourceIdentifier": "prodsec@splunk.com"
}