FKIE_CVE-2026-33557

Vulnerability from fkie_nvd - Published: 2026-04-20 14:16 - Updated: 2026-06-30 03:18
Severity
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
8.6 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
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/v57o00hm6yszdpdnvqx2ss4561yh953hMitigation, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2026/04/17/2Mailing List
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/security/cve/CVE-2026-33557
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://bugzilla.redhat.com/show_bug.cgi?id=2459739
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33557.json
Impacted products
Vendor Product Version
apache kafka *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
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          "defaultStatus": "unaffected",
          "product": "Apache Kafka",
          "vendor": "Apache Software Foundation",
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      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    }
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          "operator": "OR"
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  "cveTags": [],
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      "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": "2026-06-30T03:18:41.357",
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          "privilegesRequired": "NONE",
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
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}


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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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