CVE-2025-38386: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-38386 is a use-after-free vulnerability in the Linux kernel's ACPICA (ACPI Component Architecture) subsystem, specifically in the AML method evaluation logic. The flaw is triggered when a platform firmware update increases the number of method parameters without updating all callers, causing ACPICA to crash due to a use-after-free condition when fewer arguments than expected are passed to an AML method. It affects Linux kernel versions from 5.4 up to (but not including) 5.4.296, 5.5–5.10.240, 5.11–5.15.187, 5.16–6.1.144, 6.2–6.6.97, 6.7–6.12.37, 6.13–6.15.6, and release candidates 6.16-rc1 and 6.16-rc2. Debian Linux 11 is also listed as an affected product. The vulnerability was published on July 25, 2025, and carries a CVSS v3.1 base score of 5.5 (Medium) (Feedly).

The root cause is classified as CWE-416 (Use After Free). When a platform firmware update increases the number of parameters expected by an ACPI Machine Language (AML) method but fails to update one or more of its callers, the ACPICA interpreter attempts to evaluate the method with fewer arguments than declared. This mismatch causes the interpreter to access already-freed memory, resulting in a crash. The attack vector is local (AV:L), requires low privileges (PR:L), and no user interaction. The fix makes ACPICA refuse to evaluate a method if the caller passes fewer arguments than the method expects, preventing the interpreter from operating on invalid state (Feedly, Kernel Patch).

Successful exploitation results in a kernel crash (denial of service), with high availability impact and no confidentiality or integrity impact. Because the vulnerability is triggered via a malformed or mismatched ACPI firmware configuration, it primarily affects system stability — a local attacker or a malicious firmware update could cause the affected system to crash. There is no evidence of data exfiltration or privilege escalation potential associated with this vulnerability (Feedly).

No public proof-of-concept exploit code or in-the-wild exploitation has been reported for CVE-2025-38386. The EPSS score is approximately 0.024% (0.000240), indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires local access and is contingent on a specific firmware misconfiguration (mismatched AML method argument counts), significantly limiting its practical attack surface (Feedly).

The Linux kernel maintainers have released patches across all affected stable branches. Updated versions include: 5.4.296, 5.10.240, 5.15.187, 6.1.144, 6.6.97, 6.12.37, 6.15.6, and 6.16-rc3. Downstream distributions including Ubuntu (USN-7774-1, USN-7774-2, USN-7774-4, USN-7775-1, USN-7775-2, USN-7775-3), Amazon Linux 2, and Oracle Linux 8 have issued their own kernel update advisories. Administrators should update to the patched kernel version appropriate for their distribution as soon as possible (Ubuntu Advisory, Amazon Linux, Kernel Patch).