CVE-2023-53789: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53789 is a NULL pointer dereference vulnerability in the Linux kernel's AMD IOMMU (Input-Output Memory Management Unit) subsystem, specifically in the iommu/amd page fault handler. The flaw occurs when the IOMMU domain for a device group is not properly set up, causing the page fault handler to dereference a NULL pointer instead of gracefully handling the missing domain. Affected Linux kernel versions include all releases prior to 6.1.16, 6.2.3, and 6.3. The vulnerability was published on December 9, 2025, and carries an estimated CVSS severity of Medium with an EPSS score of 0.000170 (Feedly, EUVD).

The root cause is a missing NULL check in the AMD IOMMU interrupt thread handler (amd_iommu_int_thread), which calls report_iommu_fault() without first verifying that the IOMMU domain for the affected device group has been initialized (CWE-476: NULL Pointer Dereference). When an IOMMU page fault is triggered on a device whose domain is not set up — for example, during early initialization or misconfiguration — the kernel attempts to read from offset 0x58 of a NULL pointer, causing an Oops and kernel panic. The fix adds a domain existence check before proceeding with fault reporting, logging an appropriate diagnostic message instead of crashing. Patch commits are available at kernel stable trees for versions 6.1.16, 6.2.3, and 6.3 (Feedly, EUVD).

Successful triggering of this vulnerability causes a kernel NULL pointer dereference, resulting in a kernel panic (Oops) and system crash, directly impacting availability. The crash occurs in the IRQ thread context (irq/24-AMD-Vi), meaning it can be triggered by IOMMU page fault events on systems using AMD IOMMU with improperly configured device groups. There is no evidence of confidentiality or integrity impact beyond the denial-of-service caused by the kernel crash (Feedly).

There is no known public exploit code or evidence of in-the-wild exploitation for CVE-2023-53789. The EPSS score is very low at 0.000170, indicating a minimal probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation would require the ability to trigger an IOMMU page fault on a system where the AMD IOMMU domain is not properly configured, which is generally a local or hardware-specific condition rather than a remotely exploitable scenario (Feedly).

The Linux kernel maintainers have released patches addressing this vulnerability in stable versions 6.1.16, 6.2.3, and 6.3. Administrators should update their Linux kernel to at least one of these patched versions. The relevant patch commits are: be8301e2d5a8b95c04ae8e35d7bfee7b0f03f83a (6.2.3), 446080b353f048b1fddaec1434cb3d27b5de7efe (6.1.16), and 996d120b4de2b0d6b592bd9fbbe6e244b81ab3cc (6.3). As a temporary workaround on systems where upgrading is not immediately possible, disabling AMD IOMMU or ensuring all device groups have properly configured IOMMU domains may reduce exposure (EUVD).