CVE-2026-111073
Description
A flaw was found in Apache Kafka. The broker-side telemetry interface validates only the compressed size of incoming metrics payloads, failing to enforce a limit on the decompressed data size. An authenticated client can exploit this flaw by sending a small, highly compressed payload that expands dramatically during decompression. This excessive memory consumption can exhaust broker memory resources and crash the service, leading to a Denial of Service (DoS).
Statement
This vulnerability is rated as Moderate impact because successful exploitation requires an authenticated client and only causes a denial of service, without compromising system confidentiality or data integrity. In typical Red Hat deployments containing Apache Kafka brokers, telemetry intake is exposed to all authenticated connections without access control list enforcement. A malicious or compromised authenticated user can transmit highly compressible metrics data that expands upon decompression, exhausting broker heap memory and degrading cluster stability.
Mitigation
Lower the `telemetry.max.bytes` configuration parameter on Kafka brokers to limit the size of compressed telemetry payloads processed into memory.
In the Kafka broker configuration file (`server.properties`), set a reduced value for the telemetry payload limit (for example, 100 KB):
telemetry.max.bytes=102400
Caveats:
This provides a partial mitigation. Decreasing this parameter reduces the worst-case decompressed heap allocation proportionally, but does not completely eliminate memory amplification. In addition, legitimate clients transmitting valid telemetry metrics exceeding this configured limit will be rejected.
Warning: Modifying the broker configuration requires restarting the Kafka broker service, which can cause temporary service interruption if not performed in a rolling restart fashion across the cluster.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 6.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Amplification; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
System resources, CPU and memory, can be quickly consumed. This can lead to poor system performance or system crash.
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