Description
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.
Published: 2026-10-28
Score: n/a
EPSS: n/a
KEV: No
Impact: Broker out‑of‑memory denial of service
Action: Immediate Patch
AI Analysis

Impact

The Apache Kafka broker decompresses PushTelemetry payloads without imposing a limit on the decompressed output size. An attacker who can authenticate to the broker can send a tiny, highly compressible payload that expands to hundreds of megabytes in broker memory, causing an OutOfMemoryError and crashing the broker. Repeated or concurrent requests can exhaust the broker heap and bring down the broker, while targeting multiple brokers can degrade cluster availability. The vulnerability is not gatekeeper‑controlled, so any authenticated client can exploit it.

Affected Systems

The affected vendor is the Apache Software Foundation and the product is Apache Kafka. All Kafka broker releases prior to the patch versions 4.2.2, 4.3.1 and 4.4.0 are vulnerable. The fix is shipped in those specific patches.

Risk and Exploitability

Because the flaw requires a standard authenticated client and can be triggered over the network, the risk of exploitation is high if the broker is exposed to untrusted clients. The denial of service outcome directly compromises availability. The Advisory does not list a CVSS score or EPSS value and the vulnerability is not in the CISA KEV catalog, but the potential impact is severe and the exploitation likelihood is significant for environments that do not control client trust.

Generated by OpenCVE AI on October 28, 2026 at 17:20 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade Apache Kafka to version 4.2.2, 4.3.1, or 4.4.0 to enforce a maximum decompressed size equal to telemetry.max.bytes.
  • If an upgrade cannot be released immediately, lower the telemetry.max.bytes configuration to a tighter value to reduce the worst‑case decompressed size, accepting that this is only a partial mitigation.
  • Apply network or ACL restrictions to limit which authenticated clients can connect to the broker, thereby reducing the pool of potential attackers.

Generated by OpenCVE AI on October 28, 2026 at 17:20 UTC.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

References
Link Providers
https://kafka.apache.org/cve-list cve-icon cve-icon
History

Wed, 28 Oct 2026 16:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Apache Kafka: PushTelemetry (KIP-714) metrics payloads are decompressed without a size limit, allowing a broker out-of-memory denial of service
Weaknesses CWE-400
CWE-409
CWE-770
References

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-10-28T16:37:58.482Z

Reserved: 2026-10-15T13:40:49.926Z

Link: CVE-2026-111073

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-28T17:17:38.300

Modified: 2026-10-28T17:17:38.300

Link: CVE-2026-111073

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-28T17:30:15Z

Weaknesses
  • CWE-400

    Uncontrolled Resource Consumption

  • CWE-409

    Improper Handling of Highly Compressed Data (Data Amplification)

  • CWE-770

    Allocation of Resources Without Limits or Throttling