# CVE-2026-43240: x86/kexec: add a sanity check on previous kernel's ima kexec buffer

> A missing sanity check in the Linux kernel's x86 kexec path can cause a kernel panic when booting with a limited memory command line.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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:** 6 May 2026
- **Updated:** 19 Jun 2026
- **Also known as:** BELL-CVE-2026-43240, DEBIAN-CVE-2026-43240, GHSA-m57m-j47p-5rq9, ROOT-OS-UBUNTU-2404-CVE-2026-43240, UBUNTU-CVE-2026-43240

## What is CVE-2026-43240?

CVE-2026-43240 is a medium-severity vulnerability in Linux kernel, published on 6 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:

x86/kexec: add a sanity check on previous kernel's ima kexec buffer

When the second-stage kernel is booted via kexec with a limiting command
line such as "mem=<size>", the physical range that contains the carried
over IMA measurement list may fall outside the truncated RAM leading to a
kernel panic.

    BUG: unable to handle page fault for address: ffff97793ff47000
    RIP: ima_restore_measurement_list+0xdc/0x45a
    #PF: error_code(0x0000) – not-present page

Other architectures already validate the range with page_is_ram(), as done
in commit cbf9c4b9617b ("of: check previous kernel's ima-kexec-buffer
against memory bounds") do a similar check on x86.

Without carrying the measurement list across kexec, the attestation
would fail.

## Which versions are affected by CVE-2026-43240?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43240?

Apply the vendor's patch.

## Is CVE-2026-43240 being exploited?

There is no known exploitation of CVE-2026-43240 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-2026-43240 and fix it if it is affected.

What it is: CVE-2026-43240 is a medium-severity vulnerability in Linux kernel, published on 6 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-2026-43240 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-2026-43240/ (Markdown: https://insights.sbomify.com/CVE-2026-43240/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43240
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43240
- OSV: https://osv.dev/vulnerability/CVE-2026-43240

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43240/
Summaries are generated and may contain mistakes; the official description above is the record.