In the Linux kernel’s RDMA/EFA component, a bug in the computation of the last PBL chunk length causes that chunk to be reported as empty when its page count is an exact multiple of 510 addresses. This miscalculation leads the device to reject memory registration for that chunk, while it was fully populated. The flaw does not provide code execution, elevation of privilege, or direct data disclosure, but it does interrupt RDMA operations, effectively denying service to applications relying on direct memory access. The weakness corresponds to incomplete validation of input parameters that influence memory mapping and potential buffer overflows. The impact is limited to the termination or failure of RDMA memory registration requests, which can disrupt performance‑critical workloads.

The vulnerability affects Linux kernel distributions that include the Elastic Fabric Adapter (EFA) driver for Elastic Fabric Adapter hardware. Any kernel version before the commit that corrects the PBL chunk length computation is potentially affected. Because the effect is triggered during memory registration, systems where the EFA driver is enabled and RDMA operations are performed are at risk. Distributions that ship kernels containing the vulnerable code without later patching remain impacted until the change is incorporated.

The CVSS score of 5.5 indicates moderate severity. The EPSS score of < 1% reflects a low probability of exploitation. The vulnerability is not listed in the CISA KEV catalog, implying no confirmed large‑scale exploits. Attackers are likely to exploit the flaw by initiating RDMA memory registrations; the vector is inferred to be local or remote with RDMA access, as the flaw is triggered by the device during the registration process. No public exploit is documented, but a local user with RDMA capabilities could repeatedly attempt registration to cause service disruption.