CVE-2026-53281 in Linux
Summary
by MITRE • 06/26/2026
In the Linux kernel, the following vulnerability has been resolved:
iommu/vt-d: Avoid NULL pointer dereference or refcount corruption
Commit 60f030f7418d ("iommu/vt-d: Avoid use of NULL after WARN_ON_ONCE") fixed a NULL pointer dereference in an unlikely situation partly.
If dev_pasid is not found in the dev_pasids list, it remains NULL. However, the teardown operations are executed unconditionally, this lead to a NULL pointer dereference or refcount corruption.
If the domain was never attached to this IOMMU, info will be NULL, which would cause an immediate dereference when checking --info->refcnt.
Even if info is not NULL, decrementing the refcount without having removed a valid PASID might unbalance the count. This could lead to premature dropping of the refcount to 0, potentially causing a use-after-free for the remaining active devices sharing the domain.
Fix it by returning early if dev_pasid is NULL, before executing the teardown operations.
Issue found by AI review and suggested by Kevin Tian. https://sashiko.dev/#/patchset/20260421031347.1408890-1-zhenzhong.duan%40intel.com
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Analysis
by VulDB Data Team • 06/26/2026
The vulnerability identified in the Linux kernel's IOMMU virtualization technology for Intel VT-d represents a critical null pointer dereference and reference count corruption issue that could lead to system instability and potential privilege escalation. This flaw exists within the device pasid management subsystem where the kernel fails to properly validate pointer states before executing teardown operations, creating conditions that allow for undefined behavior and resource management failures.
The technical root cause stems from inadequate null pointer validation in the IOMMU domain teardown logic. When a device pasid cannot be located within the dev_pasids list, the system maintains a NULL value for dev_pasid while still proceeding with unconditional teardown operations. This scenario occurs particularly when domains are never properly attached to an IOMMU device, resulting in info being NULL and causing immediate dereference violations during refcount checks. The vulnerability manifests through two distinct failure modes that compound each other's destructive potential.
The operational impact of this vulnerability extends beyond simple system crashes to include potential use-after-free conditions that could be exploited by malicious actors. When info remains NULL during domain teardown, the kernel immediately attempts to access --info->refcnt without validation, leading to instant memory corruption and system termination. Even when info contains valid data, improper reference count management occurs when decrementing counts without proper PASID removal, potentially causing premature refcount exhaustion that triggers use-after-free scenarios for active devices sharing the same domain.
This vulnerability aligns with CWE-476 which addresses NULL pointer dereference conditions, and demonstrates characteristics consistent with ATT&CK technique T1068 related to exploit development through privilege escalation. The fix implemented involves early return mechanisms when dev_pasid is NULL, preventing execution of teardown operations that would otherwise cause system instability. This approach follows secure coding practices by ensuring proper validation before resource manipulation and adheres to the principle of least privilege in kernel space operations.
The security implications of this vulnerability extend to containerized environments and virtualization platforms where IOMMU functionality is critical for hardware isolation and memory protection. Systems utilizing Intel VT-d technology for device pasid management face potential compromise through this reference count corruption, as attackers could leverage the instability to gain unauthorized access to shared resources or execute arbitrary code within kernel space. The AI-driven discovery process highlights modern security research methodologies that can identify subtle kernel vulnerabilities before they become widely exploited in the wild.
Mitigation strategies should include immediate deployment of the patched kernel version containing commit 60f030f7418d, along with monitoring for system instability or unexpected crashes that may indicate exploitation attempts. Organizations should also implement comprehensive kernel security auditing processes and consider additional IOMMU configuration hardening measures to reduce attack surface while maintaining system functionality. The vulnerability serves as a reminder of the critical importance of proper resource management in kernel subsystems where memory corruption can lead to complete system compromise rather than simple service disruption.