CVE-2026-90990

MEDIUM CVSS 4.0: 5.3 EPSS 0.42%
Updated Sep 22, 2026
Checkmk
Parameter Value
CVSS 5.3 (MEDIUM)
Affected Versions 2.5.0 — 2.5.0p14
Fixed In 2.5.0p14
Type CWE-93
Vendor Checkmk
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
Low
Partial disruption

CVSS Vector v4.0

Weakness Type (CWE)

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Checkmk Checkmk
cpe:2.3:a:checkmk:checkmk:*:*:*:*:*:*:*:*
2.5.0 2.5.0p14