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Fencer Intel
medium 6.5

CVE-2026-111073 json

Apache Kafka: PushTelemetry (KIP-714) metrics payloads are decompressed without a size limit, allowing a broker out-of-memory denial of service

published 12d ago modified 4d ago also EUVD-2026-112168

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

The broker-side PushTelemetry API (KIP-714) validates only the compressed size of a client's metrics payload against telemetry.max.bytes (default 1 MB) before decompressing it. ClientTelemetryUtils.decompress() then decompresses the payload with no limit on the decompressed output size, growing a heap buffer until the compressed input is exhausted. A small, highly compressible payload (for example gzip-compressed zeros) can therefore expand to hundreds of megabytes of broker heap.

Impact:

An authenticated client can send a PushTelemetry request with a small compressed payload that decompresses to a very large size, consuming broker heap out of proportion to the request size. Repeated or concurrent requests can exhaust the broker heap and cause an OutOfMemoryError, degrading or crashing the broker; a client that targets multiple brokers can affect cluster availability. PushTelemetry is available to any authenticated client and is not gated by an ACL.

Mitigation:

Upgrade to Apache Kafka 4.2.2, 4.3.1, or 4.4.0. On affected versions there is no configuration that fully prevents the amplification, because telemetry.max.bytes bounds only the compressed size; lowering telemetry.max.bytes reduces the worst-case decompressed size proportionally and is a partial mitigation.

Resolution:

- From Apache Kafka 4.2.2, 4.3.1, and 4.4.0: ClientTelemetryUtils.decompress() enforces a maximum decompressed size equal to telemetry.max.bytes (default 1 MB). Decompression reads in bounded chunks and aborts with a TelemetryTooLargeException once the decompressed total exceeds the limit, so an over-large or highly compressible payload is rejected instead of being fully expanded in heap. The decompressed size is therefore bounded by default.

Patch / fix

  • apache kafka 4.2.2, 4.3.1
  • org.apache.kafka kafka 4.2.2, 4.3.1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-111073 updated cvss 6.5

org.apache.kafka/kafka-clients: Apache Kafka: Denial of Service via unbounded telemetry payload decompression

  • Red Hat OpenShift Serverless openshift-serverless-1/kn-ekb-receiver-rhel9, openshift-serverless-1/kn-ekb-dispatcher-rhel9 Red Hat build of Apache Camel 4 for Quarkus 3 kafka-clients 4.1.2.redhat-00001 Red Hat build of Apache Camel for Spring Boot 4 kafka-clients 4.1.2.redhat-00001 Red Hat build of Apicurio Registry 3 kafka-clients 4.1.2.redhat-00001 Red Hat build of Debezium 3 kafka-clients 4.1.2.redhat-00001 Red Hat build of Quarkus kafka-clients 4.1.2.redhat-00001
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Fuse 7 kafka-clients 4.1.2.redhat-00001
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat streams for Apache Kafka 3 kafka-clients 4.1.2.redhat-00001
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4d ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Apache Software Foundation Apache Kafka

Classification

Weakness
  • CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)
  • CWE-770 Allocation of Resources Without Limits or Throttling
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.