Vulnerability in Checkmk Gmbh

CVE-2026-90990

Improper neutralization of newlines in filter values in the monitoring host and service list APIs in Checkmk <2.5.0p14 allows an authenticated user to inject additional Livestatus query headers, bypassing object visibility restrictions in count queries to infer information about hosts and services outside their contact groups and occupying web server and Livestatus workers for an attacker-controlled duration.

Vulnerability class: CRLF Injection

Published · last modified .

EPSS exploit prediction

EPSS: 0.004 (36.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 36th percentile — 36.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-90990: held from 0.004 to 0.004.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Weakness classification (CWE)

References