CVE-2026-53297: Linux Kernel MANA Driver Null Pointer Dereference DoS

Technical summary

CVE-2026-53297 is a null pointer dereference in the Linux kernel's MANA (Microsoft Azure Network Adapter) driver's mana_remove() function. The vulnerability occurs when PM resume fails and triggers mana_remove() via mana_probe() error handling, setting gdma_context and driver_data to NULL. If the device is subsequently unbound without being automatically released, mana_remove() is invoked a second time. The second invocation dereferences gc->dev without checking whether gc is NULL, causing a kernel panic. The fix adds an early return guard if gdma_context or driver_data is NULL, and relocates the dev assignment after the guard to prevent null pointer access.

Business impact

This vulnerability impacts service availability on systems running affected Linux kernel versions with Azure MANA hardware. In cloud environments or datacenter deployments using Azure accelerated networking, a failed resume event followed by device unbind can trigger an unplanned kernel panic, causing loss of connectivity and service downtime. The impact is localized to affected systems but can cascade if the panic affects clustering or failover behavior. Organizations relying on Azure VMs with MANA NICs should prioritize patching to prevent unexpected outages.

Affected systems

The vulnerability affects systems running Linux kernels with the MANA driver implementation. This includes Azure virtual machines and bare-metal systems configured with Microsoft Azure Network Adapter hardware. The issue manifests only when power management resume operations fail and the device is subsequently unbound—a relatively specific but realistic failure path in cloud environments where VMs are suspended, migrated, or undergo hardware state transitions.

Exploitability

This is not a remotely exploitable vulnerability. Exploitation requires local system access and the ability to trigger a power management resume failure followed by device unbinding. The attack surface is limited to scenarios involving intentional or incidental power state transitions combined with driver error conditions. In normal operation without forced resume failures, the vulnerability may not manifest, but organizations should not rely on this for risk management.

Remediation

Apply a patched Linux kernel version that includes the NULL pointer check guard in mana_remove(). The fix is straightforward: adding an early return if gdma_context or driver_data is NULL, and moving the dev assignment after the guard. Verify the patch is included in the specific kernel version used in your environment by checking vendor advisories or the kernel changelog. No workaround is available; patching is the only mitigation.

Patch guidance

Obtain the patched kernel version from your Linux distribution (Red Hat, Ubuntu, SUSE, etc.) or compile from the upstream Linux kernel source after the fix date. The patch is minimal and low-risk; it adds a NULL check and reorders one assignment. Test the patched kernel in a non-production environment first, particularly if you use Azure MANA hardware or perform frequent power management operations. Coordinate deployment with your infrastructure team to minimize disruption, especially in cloud environments where kernel updates may require VM reboots.

Detection guidance

Monitor for kernel panics mentioning mana_remove or null pointer dereference in MANA driver code. Collect kernel logs and dmesg output from systems with Azure MANA hardware, especially those undergoing power management transitions or VM migration. Set up alerts for kernel panic messages containing references to mana.c or gdma_context NULL dereferences. If you observe such panics in your environment, immediately escalate to patching and consider temporarily disabling aggressive power management or device state transitions until updated.

Why prioritize this

Although the CVSS score is moderate (5.5), this vulnerability should be prioritized for organizations operating Azure cloud infrastructure or Azure-connected hardware. The impact is high in affected contexts because kernel panics directly cause service unavailability. The likelihood is moderate because it requires a specific failure sequence (resume failure plus unbind), but that sequence can occur during routine cloud operations, hardware maintenance, or VM migration. The fix is simple and low-risk, making remediation straightforward.

Risk score, explained

The CVSS 3.1 score of 5.5 (MEDIUM) reflects local attack vector, low privileges required, no special conditions, and high availability impact. The score appropriately captures that this is a reliability issue affecting local systems without confidentiality or integrity consequences. For organizations in scope (Azure infrastructure operators), the actual risk may be perceived as higher due to availability impact in production environments, justifying expedited patching despite the moderate CVSS rating.

Frequently asked questions