CVE-2026-77021CWE-409

CVE-2026-77021

published September 21, 2026

CVSS
5.3
EPSS
0%
Percentile
31.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS
5.3 · NONE
CVSS v4.0
5.3 · 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
EPSS
0.00382 · 31.0th percentile
Weakness
CWE-409 · Improper Handling of Highly Compressed Data (Data Amplification)
Published
2026-09-21T15:17Z
References (1)
https://checkmk.com/werk/22116 · [email protected]
EPSS history
Timeline
  • 23 SEP 03:48Z
    EPSS moved — → 0%
    epss
  • 21 SEP 10:57Z
    Missing decompression size limit in agent receiver allows memory exhaustion via push agent data
    cvelistv5