CVE-2026-77021
Medium
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.
SeverityMedium
CVSS5.3
Exploit probability—
ProductCheckmk
PublishedSep 21, 2026
First seenSep 21, 2026
Weakness typeCWE-409CWE-409
How to fix
Update
- Checkmk GmbH Checkmk2.5.0p14, 2.4.0p37, 2.3.0p51 or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Checkmk GmbH Checkmk | 2.5.0 ≤ v < 2.5.0p14, 2.4.0 ≤ v < 2.4.0p37, 2.3.0 ≤ v < 2.3.0p51, 2.2.0 | 2.5.0p14, 2.4.0p37, 2.3.0p51 |
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