CVE-2026-98430: 
Linux Kernel vulnerability analysis and mitigation

CVE-2026-98430 is a use-after-free / uninitialized memory access vulnerability in the Linux kernel's RDMA/efa driver, caused by a lifetime mismatch between the management IRQ handler and the admin completion queue and async event queue it accesses. The driver registered the IRQ before constructing these queues and destroyed them before freeing the IRQ, creating a window where the handler could access freed or not-yet-initialized memory. The vulnerability was introduced in Linux kernel 5.2 and disclosed on October 14, 2026. It carries an estimated CVSS severity of Medium (base score 0.0 per ENISA EUVD at time of publication, with Feedly estimating Medium) (GitHub Advisory, ENISA EUVD).

The root cause is a resource lifetime management flaw (CWE-416: Use After Free / CWE-908: Use of Uninitialized Resource) in the RDMA/efa kernel driver. The management IRQ handler is registered before the admin completion queue and async event queue are constructed, and these queues are destroyed before the IRQ is freed — meaning the IRQ handler's execution window is not bounded by the lifetime of the resources it dereferences. The fix reorders initialization: queues are set up with interrupts masked first, the IRQ is then requested, and interrupt mode is enabled afterward; on teardown, the device is reset and the IRQ freed before queues are destroyed. A similar reset is applied if IRQ registration fails, since the device already holds DMA addresses for the queues at that point (GitHub Advisory, Kernel Stable).

A local user with the ability to trigger device initialization or removal operations on a system using the EFA (Elastic Fabric Adapter) RDMA driver can cause the IRQ handler to access freed or uninitialized memory, potentially resulting in kernel crashes (denial of service), memory corruption, or arbitrary code execution at kernel privilege level. The impact is confined to systems with EFA RDMA hardware (e.g., AWS EC2 instances using EFA networking), and exploitation requires local access rather than remote attack capability (GitHub Advisory, ENISA EUVD).

There is no known public proof-of-concept exploit and no evidence of in-the-wild exploitation at the time of disclosure. The EPSS score is 0.0, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Exploitation requires local access and the presence of EFA RDMA hardware, significantly limiting the attack surface (GitHub Advisory, ENISA EUVD).

Patches have been backported to multiple stable Linux kernel branches. Users should update to the following versions or later: 6.1.189, 6.6.158, 6.12.112, 6.18.54, 7.2.8, or 7.3-rc4 (mainline). The fix commits are available in the kernel stable tree (e.g., 0a8a105978e5, 00f7df59543c, bc7e64bad96c, d2a1c0bf4139, cf5520d1c931, e08aca85c02f). Systems not using EFA RDMA hardware are not affected and require no action (GitHub Advisory, Kernel Stable).