Raw vector
CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XSummary
CVE-2025-39666 is a critical-severity Untrusted Search Path (CWE-426) vulnerability in Checkmk Checkmk. Its CVSS base score is 9.3 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked at the 2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to CM-6 (Configuration Settings) and SR-4 (Provenance) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2025-39666 is a local privilege escalation vulnerability affecting Checkmk versions 2.2.0 (end-of-life), 2.3.0 prior to 2.3.0p46, 2.4.0 prior to 2.4.0p25, and 2.5.0 (beta) prior to 2.5.0b3. It stems from CWE-426 (Untrusted Search Path) and CWE-829 (Inclusion of Functionality from Untrusted Control Sphere), enabling a site user to manipulate files within the site context. These files are subsequently processed by the `omd` administrative command executed with root privileges, allowing unauthorized escalation.
An attacker with local access and low privileges (PR:L), such as a site user, can exploit this vulnerability with low attack complexity (AC:L) but requires user interaction (UI:R). Successful exploitation grants root-level access (C:H/I:H/A:H), as indicated by the CVSS v3.1 base score of 7.3 (AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H). No remote access is needed, limiting the attack surface to compromised local accounts.
The Checkmk advisory at https://checkmk.com/werk/18891 details mitigation through patching: upgrade to Checkmk 2.3.0p46 or later, 2.4.0p25 or later, or 2.5.0b3 or later for beta users. Checkmk 2.2.0 users should migrate off the EOL version, as no patches are available.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-209262
Vulnerability Data
Local privilege escalation in Checkmk 2.2.0 (EOL), Checkmk 2.3.0 before 2.3.0p46, Checkmk 2.4.0 before 2.4.0p25, and Checkmk 2.5.0 (beta) before 2.5.0b3 allows a site user to escalate their privileges to root, by manipulating files in the site context that are…
more
processed when the `omd` administrative command is run by root.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 6 hardening rules · 6 OS baselines
V14.2.3V3.5.6V9.1.3V15.3.2
Mitigating Controls (NIST 800-53 r5) AI
Secure baseline settings can enforce absolute, organization-controlled paths for critical resources.
Requires documented, valid provenance for components, preventing acceptance of code from outside the trusted sphere.
Least-functionality configuration can prohibit unapproved directories or executables from being reachable via search paths.
Engineering principles such as trusted paths, complete mediation, and least privilege directly require hard-coded or validated search paths instead of external ones.
Implements detection and prevention of counterfeit or inauthentic components before they are integrated.
Establishes processes to identify and address supply-chain weaknesses that would allow untrusted functionality.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Pre-acquisition integrity/authenticity checks directly prevent inclusion of untrusted code.
Preventing execution of unauthorized code directly blocks the malicious binaries that an untrusted search path would load.
Supply-chain program directly governs inclusion of third-party executable code.
Contractual requirements can mandate trusted sources and integrity checks for included functionality.
Supplier risk assessment explicitly covers risks from their products and libraries.
Critical-supplier assessment reduces risk of importing executable functionality from untrusted parties.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
By requiring suppliers to propagate security requirements and to disclose component provenance, the control limits the inclusion of functionality obtained from untrusted third-party sources without oversight.
Security testing can discover search-path issues but does not itself prevent them in production code.
Restricting software installation reduces the chance that untrusted binaries or libraries are placed in search paths.
Secure architecture principles include hard-coded or validated search paths and avoiding reliance on untrusted directories.
Secure coding standards require absolute paths or integrity-checked search paths, directly mitigating CWE-426.
Blocking domains that serve malware or untrusted scripts prevents the browser from automatically including functionality from an attacker-controlled source.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (1 rule)
- V-248635 Executable search paths within the initialization files of all local interactive OL 8 users must only contain paths that resolve to the system default or the user's home directory. prevents CWE-829
Oracle Linux 9 (1 rule)
- V-271847 OL 9 must be configured so that executable search paths within the initialization files of all local interactive users must only contain paths that resolve to the system default or the users home directory. prevents CWE-829
RHEL 7 (1 rule)
- V-204477 The Red Hat Enterprise Linux operating system must be configured so that all local interactive user initialization files executable search paths contain only paths that resolve to the users home directory. prevents CWE-829
RHEL 8 (1 rule)
- V-230317 Executable search paths within the initialization files of all local interactive RHEL 8 users must only contain paths that resolve to the system default or the users home directory. prevents CWE-829
RHEL 9 (1 rule)
- V-258050 Executable search paths within the initialization files of all local interactive RHEL 9 users must only contain paths that resolve to the system default or the users home directory. prevents CWE-829
Windows 10 (1 rule)
- V-220737 Administrative accounts must not be used with applications that access the Internet, such as web browsers, or with potential Internet sources, such as email. prevents CWE-829