# 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.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`)
- **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:** Yes
- **Published:** 27 May 2026
- **Updated:** 27 May 2026
- **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

## 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 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-45851?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-45851?

Apply the vendor's patch.

## 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

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45851 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-45851 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-45851/ (Markdown: https://insights.sbomify.com/CVE-2026-45851/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45851
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45851
- OSV: https://osv.dev/vulnerability/CVE-2026-45851

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45851/
Summaries are generated and may contain mistakes; the official description above is the record.