CVE-2026-77021

Missing decompression size limit in agent receiver allows memory exhaustion via push agent data

State: Published
Severity: 5.3 Medium
Published: Sep 21, 2026
Updated: Sep 21, 2026
Reserved: Aug 20, 2026

Description

Improper handling of highly compressed data (data amplification) in Checkmk <2.5.0p14, <2.4.0p37, <2.3.0p51 and 2.2.0 (EOL) allows an attacker who controls a host registered for push mode to exhaust the memory of the agent receiver by sending a small zlib compressed payload that decompresses to an arbitrary size.

Scores

CVSS	Score	Vector	Source
4.0	5.3 Medium	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N	Checkmk

Weaknesses

CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

Affected Products

Product	Versions
CheckmkCheckmk GmbH	2.5.0 to before 2.5.0p14Affected 2.4.0 to before 2.4.0p37Affected 2.3.0 to before 2.3.0p51Affected 2.2.0Affected

References

https://checkmk.com/werk/22116vendor-advisory

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