The Linux kernel vulnerability (CVE-2026-45851) involves the reserve_unaccepted() function in the EFI subsystem, which incorrectly calculates the size of the memblock reservation for the unaccepted memory table. Specifically, it aligns the size of the table but does not account for cases where the table's starting physical address is not page-aligned. If the table starts at an offset within a page and extends beyond the aligned size, the end of the table may not be reserved, risking overwriting or inaccessibility. This flaw can cause a kernel panic in accept_memory(). The issue was observed on Intel TDX virtual machines with memory sizes exceeding 64GB. The fix involves calculating the end address first, including the unaligned start, then aligning it up to ensure full reservation coverage.

The vulnerability can cause a kernel panic due to improper memory reservation, leading to denial of service on affected systems. Confidentiality and integrity impacts are not indicated, but availability is severely affected. The issue is particularly relevant for Intel TDX VMs with large memory configurations.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should monitor vendor communications for updates. No specific temporary mitigations are provided in the available data.