CVE-2026-68419: 
Linux Kernel vulnerability analysis and mitigation

CVE-2026-68419 is a vulnerability in the Linux kernel's RDMA/irdma driver that allows a local authenticated user to invoke rereg_mr on special non-memory regions (used during QP/CQ/SRQ creation), causing the driver to emit a real CQP command with a zero-initialized mkey value, potentially leading to kernel memory corruption or system crashes. It was published on August 10, 2026, and affects Linux kernel versions from 6.6.120 through 6.6.147, as well as kernel 6.7 and later branches up to the fixed releases. Fixed versions include 6.6.148, 6.12.101, 6.18.42, 7.1.6, and 7.2. It carries a CVSS v3.1 base score of 7.8 (High) (GitHub Advisory, Red Hat Bugzilla).

The root cause is classified as CWE-791 (Incomplete Filtering of Special Elements). During QP/CQ/SRQ object creation, the irdma driver uses a two-step process: userspace allocates a buffer and registers it via the standard reg_mr mechanism, with an ABI field marking these registrations as special (no valid mkey, CQP command submission skipped). However, the driver fails to block rereg_mr calls on these special regions, so a user application can invoke rereg_mr on them, causing the driver to emit a real CQP operation with a zero-initialized mkey value of 0, resulting in undefined behavior. The attack vector is local, requires low privileges, and no user interaction (GitHub Advisory, Red Hat Bugzilla).

Successful exploitation can result in kernel memory corruption or system crashes, affecting confidentiality, integrity, and availability of the host system. A local authenticated user with access to RDMA resources can trigger this condition, potentially escalating privileges or causing a denial of service. The impact is confined to the local system (scope unchanged), but kernel-level corruption could have cascading effects on all processes and data on the affected host (GitHub Advisory, Red Hat Bugzilla).

There is no known public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time. The EPSS score is approximately 0.163%, indicating a 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 the ability to interact with RDMA resources (GitHub Advisory).

Apply the upstream kernel patches that prevent rereg_mr operations on special non-memory regions in the RDMA/irdma driver. Fixed versions are available: 6.6.148, 6.12.101, 6.18.42, 7.1.6, and 7.2. As a temporary workaround until patching is possible, restrict RDMA device access to trusted users and applications by tightening permissions on RDMA character devices or using kernel module parameters to limit exposure (GitHub Advisory, Red Hat Bugzilla).