ACPICA: Add validation for node in acpi_ns_build_normalized_path() addresses a use‑after‑free vulnerability that could allow an attacker with privileged or local access to execute arbitrary code in the Linux kernel. The flaw arose when the function did not verify that the node passed to it was valid, leaving a dangling pointer that could be dereferenced after the node was freed. This failure of memory management violates normal kernel safety guarantees and can lead to code execution or system compromise. The weakness is a classic instance of improper memory use (CWE‑416).

The vulnerability affected all Linux kernel releases that contained the unpatched ACPICA component, specifically those that had not applied the node validation change. The affected products are the Linux kernel distributed across all major distros. Exact version ranges are not listed, but the fix appears in commits identified by the developers’ Git hash. Thus any kernel derived from before those patches remains vulnerable, while later releases contain the defense.

The CVSS score of 7.7 indicates high severity, but the EPSS score is not available, and the KEV status indicates that the vulnerability is not listed in the CISA KEV catalog, so a precise risk quantification cannot be given. However, use‑after‑free bugs in the kernel can lead to privilege escalation or code execution, and historical exploitation of similar issues has been documented. If an attacker can trigger the vulnerable kernel path—likely through crafted ACPI tables or device firmware—he could gain root privileges. The system's exposure depends on whether the ACPI subsystem is active and whether the vulnerable code paths are reachable. After the patch, the risk is mitigated, though no KEV listing suggests there have been no known mass exploitation campaigns for this specific flaw.