Checkmk CVE-2026-105331

Exploitation requires ALL of the following, which substantially limit real-world risk: (1) a Checkmk agent must have the 'mk-oracle' agent plugin explicitly enabled - this is a non-default, opt-in Oracle-monitoring configuration; (2) the attacker must already possess local low-privileged access to the host (PR:L); and (3) the attacker must have write/edit access to the Oracle Instant Client binary or library path referenced by the plugin (the CWE-426 untrusted-search-path condition). The CVSS AC:H and AT:P metrics indicate additional complexity and environmental prerequisites (e.g., winning the timing of plugin execution and having mis-set permissions on the Instant Client path). Hosts without the mk-oracle plugin enabled, or where the Instant Client path is not writable by the attacker, are not exploitable.

This is a genuinely low-to-moderate priority issue despite the 'privilege escalation to total impact' framing, and the signals are internally consistent rather than conflicting. The vendor CVSS 4.0 vector (AV:L/AC:H/AT:P/PR:L/UI:N) describes a local attack requiring already-authenticated low-privileged access (PR:L), high attack complexity (AC:H), and specific attack requirements/preconditions (AT:P), which jointly cap the base score at 5.2. SSVC reinforces this: Exploitation is 'none' (no observed or public exploitation), Automatable is 'no' (cannot be mass/scripted-exploited), while Technical Impact is 'total' - meaning the ceiling is high but the path to it is narrow and manual. There is no CISA KEV listing, no POC indicator, and no EPSS score supplied in the input, so there is no evidence of real-world exploitation. The 'total' technical impact comes from the scope/subsequent-system metrics (SC:H/SI:H/SA:H) because the Checkmk agent typically runs with elevated (root/SYSTEM) privileges; the vulnerable system's own direct impact metrics are N (VC:N/VI:N/VA:N), reflecting that the damage is realized on the subsequent system context the agent runs as. Net: a real but gated local-privilege-escalation bug requiring a pre-existing foothold and a non-default plugin configuration - patch during normal maintenance, not an emergency.

A low-privileged local user on a host running a Checkmk agent that has the 'mk-oracle' plugin enabled replaces or modifies the Oracle Instant Client binary/library that the plugin references. When the agent (running with elevated privileges) next invokes the plugin, it loads the attacker-controlled client and executes the attacker's code with the agent's privileges, escalating to root/SYSTEM. No public exploit code or active exploitation has been identified at time of analysis.