Data Amplification Vulnerability in Checkmk Products

CVE-2026-77021

What is CVE-2026-77021?

An attacker can exploit a vulnerability in Checkmk versions prior to 2.5.0p14, 2.4.0p37, and 2.3.0p51, as well as the End of Life version 2.2.0, by sending a specially crafted zlib compressed payload that decompresses to an arbitrary size. This improper handling of highly compressed data allows the attacker to exhaust the memory resources of the agent receiver, leading to potential denial-of-service conditions. Organizations using affected versions should implement necessary security measures and consider updates to mitigate this risk.

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