CVE-2026-33557: A possible security vulnerability has been identified in Apache Kafka. By default, the broker property `sasl.

Q: How do I fix CVE-2026-33557?

kafka: upgrade to 4.1.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-33557 being exploited?

CVE-2026-33557 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-33557 affect?

CVE-2026-33557 affects kafka. Severity is critical (CVSS 9.1). 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

Q: How urgent is CVE-2026-33557?

Priority 57/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

This month

CRITICAL 9.1REMOTEWATCHLISTUPGRADE

CVE-2026-33557 is a critical-severity flaw (CVSS 9.1) affecting kafka. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 Kaf

Why this priority

Critical severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 41%)
CISA exploited list	No
Weakness	CWE-1285, CWE-303
Published	2026-04-20
Last modified	2026-10-26

Publisher (CNA): Apache Software Foundation · Vendor: apache

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-20 14:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

apache kafka UPGRADE

Affected: >= 4.1.0 and < 4.1.2

Fixed in: 4.1.2

Safe to downgrade to: a release before 4.1.0

1. Check installed version

apt-cache policy kafka || rpm -q kafka || kafka --version

2. UPGRADE to 4.1.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade kafka

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade kafka

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.1.0 (Debian / Ubuntu)

apt-cache madison kafka sudo apt install kafka=<VERSION_BEFORE_4.1.0> sudo apt-mark hold kafka

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list kafka sudo dnf downgrade kafka-<VERSION_BEFORE_4.1.0> sudo dnf versionlock add kafka

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Maven · org.apache.kafka:kafka-clients · FIXED · 4.1.2 · vulnerable: >= 4.1.0, < 4.1.2 · source

Set org.apache.kafka:kafka-clients to 4.1.2 or later in pom.xml or build.gradle, then rebuild and redeploy.

Fedora ELN · openbao · FIXED · 2.6.5-1.eln159 · FEDORA-2026-77adf886ae · source

sudo dnf upgrade --advisory=FEDORA-2026-77adf886ae

Fedora 46 · sugar-turtleart · FIXED · 220-16.fc46 · FEDORA-2026-b79483c788 · source

sudo dnf upgrade --advisory=FEDORA-2026-b79483c788

RHEL 8 · log4j:2/log4j · NOT AFFECTED

RHEL 9 · log4j · NOT AFFECTED

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-33557?

kafka: upgrade to 4.1.2. Exact commands for each OS are on this page.

Is CVE-2026-33557 being exploited?

CVE-2026-33557 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-33557 affect?

CVE-2026-33557 affects kafka. Severity is critical (CVSS 9.1). 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

How urgent is CVE-2026-33557?

Priority 57/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Apache Kafka vulnerabilities

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References

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