# CVE-2026-111073: Apache Kafka broker heap exhaustion in PushTelemetry API

Source: https://junglewise.ai/threats/cve-2026-111073-the-broker-side-pushtelemetry-api-kip-714-validates-only-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-28. Updated: 2026-10-28  
License: CC BY 4.0 with a link back

CVE-2026-111073 · Severity: info · Published 2026-10-28

Apache Kafka's PushTelemetry API (used for sending client metrics to brokers) validates only the compressed size of incoming payloads, not the decompressed size. An authenticated attacker can send a small compressed file containing highly compressible data that expands to hundreds of megabytes when decompressed, consuming broker memory. Repeated attacks can crash brokers and disrupt cluster availability.

Technologies: [Apache Kafka](https://junglewise.ai/threats/technologies/kafka). Vendors: [Apache](https://junglewise.ai/threats/vendors/apache).

## Quick answers

**Is CVE-2026-111073 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-111073 being exploited in the wild.

**How severe is CVE-2026-111073?** Informational severity, published 28 October 2026.

**Which products and versions are affected?** Apache Kafka before 4.2.2, 4.3.1, or 4.4.0.

**Is there a fix for CVE-2026-111073?** Yes: fixed in Apache Kafka 4.2.2, 4.3.1, 4.4.0. Until then: Lowering the telemetry.max.bytes configuration reduces the worst-case decompressed payload size proportionally and provides partial mitigation on affected versions until upgrade is possible. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-111073 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-111073?** Check whether you run Apache Kafka at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Apache Kafka 4.2.2, 4.3.1, 4.4.0

Lowering the telemetry.max.bytes configuration reduces the worst-case decompressed payload size proportionally and provides partial mitigation on affected versions until upgrade is possible.

## Technical details

The vulnerability exists in ClientTelemetryUtils.decompress(), which lacks a limit on decompressed output size; only the compressed payload size is validated against telemetry.max.bytes (default 1 MB). An attacker with valid credentials can send a small, highly compressible payload (e.g., gzip-compressed zeros) that decompresses to hundreds of megabytes, exhausting broker heap. Multiple requests targeting all brokers in a cluster can trigger OutOfMemoryError and availability degradation.

## Affected products

- Apache Kafka before 4.2.2, 4.3.1, or 4.4.0

## Timeline

- 2026-10-28: disclosed

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