Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2025-64999

Severity CVSS v4.0:
HIGH
Type:
CWE-79 Cross-Site Scripting (XSS)
Publication date:
26/02/2026
Last modified:
05/03/2026

Description

Improper neutralization of input in Checkmk versions 2.4.0 before 2.4.0p22, and 2.3.0 before 2.3.0p43 allows an attacker that can manipulate a host's check output to inject malicious JavaScript into the Synthetic Monitoring HTML logs, which can then be accessed via a crafted phishing link.

Impact

Vector 4.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N CVSS v4.0 Severity and Metrics:

Base Score: 7.30 HIGH
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): Present
Privileges Required (PR): Low
User Interaction (UI): Active
Confidentiality (VC): High
Integrity (VI): High
Availability (VA): High
Confidentiality (SC): None
Integrity (SI): Low
Availability (SA): None

Base Score 4.0
7.30
Severity 4.0
HIGH
Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 5.40 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): Required
Scope (S): Changed
Confidentiality (C): Low
Integrity (I): Low
Availability (A): None

Base Score 3.x
5.40
Severity 3.x
MEDIUM

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:checkmk:checkmk:2.3.0:-:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:b1:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:b2:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:b3:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:b4:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:b5:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:b6:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:p1:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:p10:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:p11:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:p12:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:p13:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:p14:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:p15:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.3.0:p16:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools