FKIE_CVE-2026-33557

Vulnerability from fkie_nvd - Published: 2026-04-20 14:16 - Updated: 2026-04-22 14:14
Severity ?
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Summary
A possible security vulnerability has been identified in Apache Kafka. By default, the broker property `sasl.oauthbearer.jwt.validator.class` is set to `org.apache.kafka.common.security.oauthbearer.DefaultJwtValidator`. It accepts any JWT token without validating its signature, issuer, or audience. An attacker can generate a JWT token from any issuer with the `preferred_username` set to any user, and the broker will accept it. We advise the Kafka users using kafka v4.1.0 or v4.1.1 to set the config `sasl.oauthbearer.jwt.validator.class` to `org.apache.kafka.common.security.oauthbearer.BrokerJwtValidator` explicitly to avoid this vulnerability. Since Kafka v4.1.2 and v4.2.0 and later, the issue is fixed and will correctly validate the JWT token.
References
security@apache.orghttps://kafka.apache.org/cve-listVendor Advisory
security@apache.orghttps://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953hVendor Advisory, Mitigation
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2026/04/17/2Mailing List
Impacted products
Vendor Product Version
apache kafka *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:apache:kafka:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "5D700BB3-89AD-4488-8820-17C427E7983D",
              "versionEndExcluding": "4.1.2",
              "versionStartIncluding": "4.1.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A possible security vulnerability has been identified in Apache Kafka.\n\nBy default, the broker property `sasl.oauthbearer.jwt.validator.class` is\u00a0set to `org.apache.kafka.common.security.oauthbearer.DefaultJwtValidator`. It accepts any JWT token without validating its\u00a0signature, issuer, or audience. An attacker can generate a JWT\u00a0token from any issuer with the `preferred_username` set to any user, and the broker will accept it.\n\nWe advise the Kafka users using kafka v4.1.0 or v4.1.1 to set the config `sasl.oauthbearer.jwt.validator.class` to `org.apache.kafka.common.security.oauthbearer.BrokerJwtValidator` explicitly to avoid this vulnerability. Since Kafka v4.1.2 and v4.2.0 and later, the issue is fixed and will correctly validate the JWT token."
    }
  ],
  "id": "CVE-2026-33557",
  "lastModified": "2026-04-22T14:14:52.030",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.2,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-04-20T14:16:18.780",
  "references": [
    {
      "source": "security@apache.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://kafka.apache.org/cve-list"
    },
    {
      "source": "security@apache.org",
      "tags": [
        "Vendor Advisory",
        "Mitigation"
      ],
      "url": "https://lists.apache.org/thread/v57o00hm6yszdpdnvqx2ss4561yh953h"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Mailing List"
      ],
      "url": "http://www.openwall.com/lists/oss-security/2026/04/17/2"
    }
  ],
  "sourceIdentifier": "security@apache.org",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1285"
        }
      ],
      "source": "security@apache.org",
      "type": "Secondary"
    }
  ]
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

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.