# CVE-2024-36936: efi/unaccepted: touch soft lockup during memory accept

> A flaw in the Linux kernel's EFI memory acceptance logic can cause soft lockups, leading to a denial of service on systems with large memory.

- **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:** 30 May 2024
- **Updated:** 23 May 2026
- **Also known as:** BELL-CVE-2024-36936, DEBIAN-CVE-2024-36936, UBUNTU-CVE-2024-36936

## What is CVE-2024-36936?

CVE-2024-36936 is a medium-severity denial of service vulnerability in Linux kernel, published on 30 May 2024. 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/unaccepted: touch soft lockup during memory accept

Commit 50e782a86c98 ("efi/unaccepted: Fix soft lockups caused by
parallel memory acceptance") has released the spinlock so other CPUs can
do memory acceptance in parallel and not triggers softlockup on other
CPUs.

However the softlock up was intermittent shown up if the memory of the
TD guest is large, and the timeout of softlockup is set to 1 second:

 RIP: 0010:_raw_spin_unlock_irqrestore
 Call Trace:
 ? __hrtimer_run_queues
 <IRQ>
 ? hrtimer_interrupt
 ? watchdog_timer_fn
 ? __sysvec_apic_timer_interrupt
 ? __pfx_watchdog_timer_fn
 ? sysvec_apic_timer_interrupt
 </IRQ>
 ? __hrtimer_run_queues
 <TASK>
 ? hrtimer_interrupt
 ? asm_sysvec_apic_timer_interrupt
 ? _raw_spin_unlock_irqrestore
 ? __sysvec_apic_timer_interrupt
 ? sysvec_apic_timer_interrupt
 accept_memory
 try_to_accept_memory
 do_huge_pmd_anonymous_page
 get_page_from_freelist
 __handle_mm_fault
 __alloc_pages
 __folio_alloc
 ? __tdx_hypercall
 handle_mm_fault
 vma_alloc_folio
 do_user_addr_fault
 do_huge_pmd_anonymous_page
 exc_page_fault
 ? __do_huge_pmd_anonymous_page
 asm_exc_page_fault
 __handle_mm_fault

When the local irq is enabled at the end of accept_memory(), the
softlockup detects that the watchdog on single CPU has not been fed for
a while. That is to say, even other CPUs will not be blocked by
spinlock, the current CPU might be stunk with local irq disabled for a
while, which hurts not only nmi watchdog but also softlockup.

Chao Gao pointed out that the memory accept could be time costly and
there was similar report before. Thus to avoid any softlocup detection
during this stage, give the softlockup a flag to skip the timeout check
at the end of accept_memory(), by invoking touch_softlockup_watchdog().

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2024-36936?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-36936?

Apply the vendor's patch.

## Is CVE-2024-36936 being exploited?

There is no known exploitation of CVE-2024-36936 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-2024-36936 and fix it if it is affected.

What it is: CVE-2024-36936 is a medium-severity denial of service vulnerability in Linux kernel, published on 30 May 2024. 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-2024-36936 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-2024-36936/ (Markdown: https://insights.sbomify.com/CVE-2024-36936/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-36936
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-36936
- OSV: https://osv.dev/vulnerability/CVE-2024-36936

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-36936/
Summaries are generated and may contain mistakes; the official description above is the record.