Advisory [CVE-2026-111073] Apache Kafka: 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
This security Apache Software Foundation advisory covers CVE-2026-111073 affecting Apache Kafka.
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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.
Affected product named by the advisory: Apache Kafka.
- Apache Kafka 3.7.0 through 4.1.2
- Apache Kafka 4.2.0 through 4.2.1
- Apache Kafka 4.3.0
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
- 4.2.2
- 4.3.1
- 4.4.0
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Mitigation checklist
- ClientTelemetryUtils.decompress() then decompresses the payload with no limit on the decompressed output size, growing a heap buffer until the compressed input is exhausted.
- Mitigation: Upgrade to Apache Kafka 4.2.2, 4.3.1, or 4.4.0.
- 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.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
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