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Vulnerabilities

Vulnerability · CVE-2026-33557

A possible security vulnerability has been identified in Apache Kafka.

Published Apr 20, 2026 · catalog updated Jul 15, 2026 · A possible security vulnerability

Check if you run it

No confirmed exploitation is on record for CVE-2026-33557. EPSS is 0.93%. Act only if a listed version of A possible security vulnerability is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A possible security vulnerability).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.93%
Remediation
Advisory link
Affected products
cpe apache/kafka

A possible security vulnerability has been identified in Apache Kafka. By default, the broker property is set to . It accepts any JWT token without validating its signature, issuer, or audience. An attacker can generate a JWT token from any issuer with the 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 to 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe apache/kafkaversion unspecified

How to fix CVE-2026-33557

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-33557. EPSS is 0.93%. Act only if a listed version of A possible security vulnerability is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1285; CWE-303. EPSS 0.93%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 20, 2026 · NIST NVD

    Detected

    A possible security vulnerability has been identified in Apache Kafka. By default, the broker property is set to . It accepts any JWT token without validating its signature, issuer, or audience. An attacker can generate a JWT token from any issuer with the 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 to explicitly to avoid

  2. Jul 15, 2026 · NIST NVD

    Updated

    A possible security vulnerability has been identified in Apache Kafka. By default, the broker property is set to . It accepts any JWT token without validating its signature, issuer, or audience. An attacker can generate a JWT token from any issuer with the 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 to explicitly to avoid

Sources

  • CVE.orgVulnerability recordCVE-2026-33557

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-33557

    30-day exploitation probability 0.9%

    first.org
  • NIST NVDVulnerability recordCVE-2026-33557

    A possible security vulnerability has been identified in Apache Kafka. By default, the broker property is set to . It accepts any JWT token without validating its signature,

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.