CVE-2026-45851 efi: Fix reservation of unaccepted memory table
A Linux kernel bug in EFI memory reservation can cause kernel panics in Intel TDX VMs with large memory sizes due to unaligned table boundaries.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-45851?
CVE-2026-45851 is a high-severity memory corruption vulnerability in Linux kernel, published on 27 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
efi: Fix reservation of unaccepted memory table
The reserve_unaccepted() function incorrectly calculates the size of the memblock reservation for the unaccepted memory table. It aligns the size of the table, but fails to account for cases where the table's starting physical address (efi.unaccepted) is not page-aligned.
If the table starts at an offset within a page and its end crosses into a subsequent page that the aligned size does not cover, the end of the table will not be reserved. This can lead to the table being overwritten or inaccessible, causing a kernel panic in accept_memory().
This issue was observed when starting Intel TDX VMs with specific memory sizes (e.g., > 64GB).
Fix this by calculating the end address first (including the unaligned start) and then aligning it up, ensuring the entire range is covered by the reservation.
Weakness: CWE-125
Which versions are affected by CVE-2026-45851?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-45851?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-45851 being exploited?
There is no known exploitation of CVE-2026-45851 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-45851, DEBIAN-CVE-2026-45851, GHSA-r9jv-8h68-mr7c, ROOT-OS-UBUNTU-2404-CVE-2026-45851, UBUNTU-CVE-2026-45851.