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HighVulnerabilityCVE-2026-111108updated 28 Oct 2026, 17:46 UTC

Apache Kafka brokers can crash from oversized array requests

A specially crafted request can make a Kafka broker run out of memory and crash. On listeners without a login requirement, anyone who can reach the broker can attempt this.

Fixed in Apache Kafka 4.2.2, 4.3.2, 4.4.0Official, 2 sources
SeverityHighVulnerability
Being exploited?UnclearNo reports either way yet
Fix available?YesApache Kafka 4.2.2, 4.3.2, 4.4.0 · since 28 Oct 2026
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1Attacker sends requestDeclares a huge array length
  2. 2Broker pre-allocatesHeap allocated before any auth check
  3. 3Heap exhaustedSeveral concurrent requests fill memory
  4. 4Broker crashesOutOfMemoryError stops the broker
  5. ResultBroker goes down (denial of service)

What happened

Kafka's generated protocol readers pre-size arrays from a sender-declared element count that is only checked against remaining buffer bytes, causing heap allocation several times larger than the request (about 8x in the reporter's test).

Why it is dangerous: A broker crash (OutOfMemoryError) disrupts all producers and consumers using it. Unauthenticated listeners such as PLAINTEXT are exposed to anyone who can reach them.

Are you affected?

You are affected if you run Apache Kafka 3.3.0 through 4.1.2, 4.2.0 through 4.2.1, or 4.3.0 through 4.3.1 with any broker listener reachable by untrusted clients.

Apache Kafka 3.3.0 - 4.1.2; 4.2.0 - 4.2.1; 4.3.0 - 4.3.1

What to do

  1. Upgrade Apache Kafka to 4.2.2, 4.3.2, or 4.4.0
  2. Until upgraded, lower socket.request.max.bytes
  3. Restrict network access to broker listeners to trusted clients only

Timeline

  1. 28 Oct 2026, 17:17 UTC
    Publicly disclosed
  2. 28 Oct 2026, 17:29 UTC
    Reported by oss-security · oss-security
  3. 28 Oct 2026, 17:31 UTC
    Reported by oss-security · oss-security
  4. 28 Oct 2026, 17:32 UTC
    Picked up by Zero Radar
  5. 28 Oct 2026, 17:34 UTC
    Reported by oss-security · oss-security
  6. 28 Oct 2026, 17:36 UTC
    NVD reported on it · NVD

Sources 4 reports, oldest first

Official vendor, government CERT or advisory database

Security researchers research teams and mailing lists

Technical details

ID
CVE-2026-111108
Disclosed
28 Oct 2026, 17:17 UTC
On Zero Radar
28 Oct 2026, 17:32 UTC (14 min after disclosure)
Last change
28 Oct 2026, 17:46 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Apache Kafka brokers can crash from oversized array requests · Zero Radar