CVE-2026-35554: A race condition in the Apache Kafka Java producer client’s buffer pool management can cause messages to be si

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HIGH 8.7REMOTEWATCHLISTUPGRADE

CVE-2026-35554 is a high-severity flaw (CVSS 8.7) affecting kafka. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A race condition in the Apache Kafka Java producer client’s buffer pool management can cause messages to be silently delivered to incorrect topics. When a produce batch expires due to delivery.timeout.ms while a network request containing that batch is still in flight, the batch’s ByteBuffer is prematurely deallocated and returned to the buffer pool. If a subsequent producer batch—potentially destined for a different topic—reuses this freed buff

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	8.7 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 62%)
CISA exploited list	No
Weakness	CWE-362, CWE-416
Published	2026-04-07
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

2026-04-07 14:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

apache kafka UPGRADE

Affected: >= 2.8.0 and < 3.9.2 · >= 4.0.0 and < 4.0.2 · >= 4.1.0 and < 4.1.2

Fixed in: 3.9.2, 4.0.2, 4.1.2

Safe to downgrade to: a release before 2.8.0

1. Check installed version

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

2. UPGRADE to 3.9.2 (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 2.8.0 (Debian / Ubuntu)

apt-cache madison kafka sudo apt install kafka=<VERSION_BEFORE_2.8.0> 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_2.8.0> 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.

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-2026-35554?

kafka: upgrade to 3.9.2, 4.0.2, 4.1.2. Exact commands for each OS are on this page.

Is CVE-2026-35554 being exploited?

CVE-2026-35554 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-2026-35554 affect?

CVE-2026-35554 affects kafka. Severity is high (CVSS 8.7). A race condition in the Apache Kafka Java producer client’s buffer pool management can cause messages to be silently delivered to incorrect topics. When a produce batch expires due to delivery.timeout.ms while a network request containing

How urgent is CVE-2026-35554?

Priority 50/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Java vulnerabilities · Apache Kafka vulnerabilities

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References

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