CVE-2026-74296 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
RDMA/mlx5: Release the HW‑provided UAR index rather than the SW one
Free the UAR index returned by the hardware.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability in question relates to a memory management issue within the Linux kernel's RDMA/mlx5 driver component which handles Mellanox ConnectX network adapters. This flaw represents a resource leak scenario where the system fails to properly release hardware-managed resources, specifically User Access Regions (UAR) that are allocated by the hardware but tracked incorrectly by software components.
The technical root cause stems from improper resource lifecycle management within the mlx5 driver implementation. When hardware allocates UAR indices for memory mapping operations, these resources must be explicitly released back to the hardware pool upon completion of their use. However, the vulnerability manifests when the system frees a software-managed copy of the UAR index instead of the actual hardware-provided index, leading to a situation where the hardware resource remains allocated and unavailable for subsequent operations.
This resource leak directly impacts system stability and performance by consuming hardware resources unnecessarily over time. As multiple RDMA operations occur, each failing to properly release hardware UAR indices creates a progressive degradation in available resources. The operational consequences extend beyond simple memory consumption issues as this can lead to resource exhaustion scenarios that prevent new RDMA connections from being established or cause existing connections to fail.
The vulnerability aligns with CWE-404 which addresses improper resource management and the specific category of resource leak patterns commonly found in kernel drivers. From an attack perspective, this represents a denial-of-service vector where sustained exploitation could lead to system instability and complete loss of RDMA functionality. The issue particularly affects systems running high-throughput networking workloads that heavily utilize Mellanox RDMA capabilities.
Mitigation strategies focus on ensuring proper resource management within the driver code by implementing correct indexing logic that tracks hardware-provided resources accurately. The fix requires modifying the resource release mechanism to properly reference the hardware-provided UAR index rather than software-managed copies, effectively addressing the fundamental mismatch in resource tracking and release operations. System administrators should ensure kernel updates are applied promptly to address this vulnerability and maintain optimal RDMA performance while preventing potential service disruption.
The remediation approach follows established kernel development practices for resource management and aligns with ATT&CK technique T1499 which covers resource exhaustion attacks, ensuring that proper memory management prevents both immediate system instability and long-term degradation of network infrastructure capabilities.