Kafka auth bypass is widely used; exploit could disrupt orgs by unauthorized access to data/topics.
CVE-2026-33557
Kafka default JWT validator bypasses signature/issuer checks.
Is CVE-2026-33557 being exploited?
Not confirmed. CVE-2026-33557 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.68% probability of exploitation in the next 30 days.
How severe is CVE-2026-33557?
CVE-2026-33557 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-33557?
Yes. A fix has been recorded for CVE-2026-33557. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-33557 affect?
CVE-2026-33557 affects Apache Kafka broker (v4.1.0, v4.1.1). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-33557?
Upgrade to 4.1.2+ and enforce BrokerJwtValidator
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
JWT auth bypass lets attacker impersonate any user and access Kafka topics/resources.
Immediate action required
- affected>= 4.1.0 and <= 4.1.1
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.