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.
- 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-2026-43240?
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 include 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
Sources
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.