CVE-2026-77021 | BDVDB-2026-377398 Detail

CheckmkCheckmk

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.

Impact#

CAPEC-197: Exponential Data Expansion

Weaknesses#

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

References#

https://checkmk.com/werk/22116

Exploit#

No public exploit known

History#

Version 12026-09-21Record published in the CVE List.

Published

Published: 2026-09-21
Last modified: 2026-09-21

Vendor information

Vendor: Checkmk
Product: Checkmk

All Checkmk vulnerabilities

Score

5.3 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 32.5.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
>= 2.5.0 and < 2.5.0p14
Fixed
2.5.0p14
Vulnerable
>= 2.4.0 and < 2.4.0p37
Fixed
2.4.0p37
Vulnerable
>= 2.3.0 and < 2.3.0p51
Fixed
2.3.0p51
Vulnerable
2.2.0
Fixed
Not stated

Scoring System

CVSS v4.0

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

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Attack Requirements	None
Privileges Required	Low
User Interaction	None
Vulnerable System Confidentiality	None
Vulnerable System Integrity	None
Vulnerable System Availability	Low
Subsequent System Confidentiality	None
Subsequent System Integrity	None
Subsequent System Availability	None

CVSS v3.1

Not available

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).