CVE-2026-24281 (GCVE-0-2026-24281)

Vulnerability from cvelistv5 – Published: 2026-03-07 08:50 – Updated: 2026-03-10 17:37
VLAI
Title
Apache ZooKeeper: Reverse-DNS fallback enables hostname verification bypass in ZooKeeper ZKTrustManager
Summary
Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.
Severity
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-350 - Reliance on Reverse DNS Resolution for a Security-Critical Action
  • CWE-295 - Improper Certificate Validation
Assigner
References
Impacted products
Vendor Product Version
Apache Software Foundation Apache ZooKeeper Affected: 3.9.0 , ≤ 3.9.4 (maven)
Affected: 3.8.0 , ≤ 3.8.5 (maven)
Create a notification for this product.
Credits
Nikita Markevich <markevich.nikita1@gmail.com>
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2026-03-07T17:05:10.486Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "http://www.openwall.com/lists/oss-security/2026/03/07/4"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "HIGH",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 5.9,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "NONE",
              "integrityImpact": "HIGH",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-24281",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-10T17:36:42.765646Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-10T17:37:28.087Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://repo.maven.apache.org/maven2",
          "defaultStatus": "unaffected",
          "packageName": "org.apache.zookeeper:zookeeper",
          "product": "Apache ZooKeeper",
          "vendor": "Apache Software Foundation",
          "versions": [
            {
              "lessThanOrEqual": "3.9.4",
              "status": "affected",
              "version": "3.9.0",
              "versionType": "maven"
            },
            {
              "lessThanOrEqual": "3.8.5",
              "status": "affected",
              "version": "3.8.0",
              "versionType": "maven"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "Nikita Markevich \u003cmarkevich.nikita1@gmail.com\u003e"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It\u0027s important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e"
            }
          ],
          "value": "Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It\u0027s important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols."
        }
      ],
      "metrics": [
        {
          "other": {
            "content": {
              "text": "important"
            },
            "type": "Textual description of severity"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-350",
              "description": "CWE-350 Reliance on Reverse DNS Resolution for a Security-Critical Action",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-295",
              "description": "CWE-295 Improper Certificate Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-07T08:50:32.525Z",
        "orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
        "shortName": "apache"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://lists.apache.org/thread/088ddsbrzhd5lxzbqf5n24yg0mwh9jt2"
        }
      ],
      "source": {
        "defect": [
          "ZOOKEEPER-4986"
        ],
        "discovery": "UNKNOWN"
      },
      "title": "Apache ZooKeeper: Reverse-DNS fallback enables hostname verification bypass in ZooKeeper ZKTrustManager",
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
    "assignerShortName": "apache",
    "cveId": "CVE-2026-24281",
    "datePublished": "2026-03-07T08:50:32.525Z",
    "dateReserved": "2026-01-21T19:40:25.776Z",
    "dateUpdated": "2026-03-10T17:37:28.087Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-24281",
      "date": "2026-06-05",
      "epss": "0.0003",
      "percentile": "0.09065"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-24281\",\"sourceIdentifier\":\"security@apache.org\",\"published\":\"2026-03-07T09:16:07.437\",\"lastModified\":\"2026-03-10T18:18:17.727\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It\u0027s important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.\"},{\"lang\":\"es\",\"value\":\"La verificaci\u00f3n de nombre de host en Apache ZooKeeper ZKTrustManager recurre a DNS inverso (PTR) cuando falla la validaci\u00f3n IP SAN, permitiendo a los atacantes que controlan o falsifican registros PTR suplantar servidores o clientes de ZooKeeper con un certificado v\u00e1lido para el nombre PTR. Es importante se\u00f1alar que el atacante debe presentar un certificado que sea de confianza para ZKTrustManager, lo que hace que el vector de ataque sea m\u00e1s dif\u00edcil de explotar. Se recomienda a los usuarios actualizar a la versi\u00f3n 3.8.6 o 3.9.5, que corrige este problema al introducir una nueva opci\u00f3n de configuraci\u00f3n para deshabilitar la b\u00fasqueda de DNS inverso en los protocolos de cliente y qu\u00f3rum.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N\",\"baseScore\":7.4,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.2,\"impactScore\":5.2},{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N\",\"baseScore\":5.9,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.2,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"security@apache.org\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-295\"},{\"lang\":\"en\",\"value\":\"CWE-350\"}]},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-295\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:apache:zookeeper:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"3.8.0\",\"versionEndExcluding\":\"3.8.6\",\"matchCriteriaId\":\"1D3E8670-F4DD-400A-A459-9396353D5E7A\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:apache:zookeeper:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"3.9.0\",\"versionEndExcluding\":\"3.9.5\",\"matchCriteriaId\":\"69917DB8-268C-4F60-AFAE-51FB24101BFE\"}]}]}],\"references\":[{\"url\":\"https://lists.apache.org/thread/088ddsbrzhd5lxzbqf5n24yg0mwh9jt2\",\"source\":\"security@apache.org\",\"tags\":[\"Mailing List\",\"Vendor Advisory\"]},{\"url\":\"http://www.openwall.com/lists/oss-security/2026/03/07/4\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CVE Program Container\", \"references\": [{\"url\": \"http://www.openwall.com/lists/oss-security/2026/03/07/4\"}], \"providerMetadata\": {\"orgId\": \"af854a3a-2127-422b-91ae-364da2661108\", \"shortName\": \"CVE\", \"dateUpdated\": \"2026-03-07T17:05:10.486Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 5.9, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"HIGH\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-24281\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-03-10T17:36:42.765646Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-03-10T17:37:12.949Z\"}}], \"cna\": {\"title\": \"Apache ZooKeeper: Reverse-DNS fallback enables hostname verification bypass in ZooKeeper ZKTrustManager\", \"source\": {\"defect\": [\"ZOOKEEPER-4986\"], \"discovery\": \"UNKNOWN\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"reporter\", \"value\": \"Nikita Markevich \u003cmarkevich.nikita1@gmail.com\u003e\"}], \"metrics\": [{\"other\": {\"type\": \"Textual description of severity\", \"content\": {\"text\": \"important\"}}}], \"affected\": [{\"vendor\": \"Apache Software Foundation\", \"product\": \"Apache ZooKeeper\", \"versions\": [{\"status\": \"affected\", \"version\": \"3.9.0\", \"versionType\": \"maven\", \"lessThanOrEqual\": \"3.9.4\"}, {\"status\": \"affected\", \"version\": \"3.8.0\", \"versionType\": \"maven\", \"lessThanOrEqual\": \"3.8.5\"}], \"packageName\": \"org.apache.zookeeper:zookeeper\", \"collectionURL\": \"https://repo.maven.apache.org/maven2\", \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://lists.apache.org/thread/088ddsbrzhd5lxzbqf5n24yg0mwh9jt2\", \"tags\": [\"vendor-advisory\"]}], \"x_generator\": {\"engine\": \"Vulnogram 0.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It\u0027s important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It\u0027s important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-350\", \"description\": \"CWE-350 Reliance on Reverse DNS Resolution for a Security-Critical Action\"}]}, {\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-295\", \"description\": \"CWE-295 Improper Certificate Validation\"}]}], \"providerMetadata\": {\"orgId\": \"f0158376-9dc2-43b6-827c-5f631a4d8d09\", \"shortName\": \"apache\", \"dateUpdated\": \"2026-03-07T08:50:32.525Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-24281\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-03-10T17:37:28.087Z\", \"dateReserved\": \"2026-01-21T19:40:25.776Z\", \"assignerOrgId\": \"f0158376-9dc2-43b6-827c-5f631a4d8d09\", \"datePublished\": \"2026-03-07T08:50:32.525Z\", \"assignerShortName\": \"apache\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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.