{"id":"CVE-2026-77021","title":"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 se…","summary":"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 se…","severity":"medium","cvss":5.3,"cvssVector":"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","cwe":["CWE-409"],"vendor":"Checkmk GmbH","product":"Checkmk","affected":["Checkmk >= 2.5.0 < 2.5.0p14","Checkmk >= 2.4.0 < 2.4.0p37","Checkmk >= 2.3.0 < 2.3.0p51","Checkmk 2.2.0"],"published":"2026-09-21","updated":"2026-09-21","sourceUpdated":"2026-09-21T20:17:32.393","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-77021","references":[{"url":"https://checkmk.com/werk/22116","label":"security@checkmk.com"}],"tags":["nvd","cve.org"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-21T14:40:45.554408Z"},"cvssSource":"cna","ingestedAt":"2026-09-21T11:35:54.432Z","epss":0.00382,"epssPercentile":0.29384,"slug":"CVE-2026-77021","body":"## Overview\n\nImproper 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":29,"depthScoreParts":{"impact":29.2,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}