# CVE-2025-39763: ACPI: APEI: send SIGBUS to current task if synchronous memory error not recovered

> A local attacker can trigger a system reboot or hard lockup by causing unhandled synchronous memory errors, leading to denial of service.

- **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:** 11 Sep 2025
- **Updated:** 23 May 2026
- **Also known as:** AZL-67217, AZL-70825, BELL-CVE-2025-39763, DEBIAN-CVE-2025-39763, GHSA-g7f2-49vp-j5f7, ROOT-OS-DEBIAN-11-CVE-2025-39763, ROOT-OS-DEBIAN-12-CVE-2025-39763, ROOT-OS-UBUNTU-2204-CVE-2025-39763, ROOT-OS-UBUNTU-2404-CVE-2025-39763, UBUNTU-CVE-2025-39763

## What is CVE-2025-39763?

CVE-2025-39763 is a medium-severity denial of service vulnerability in Linux kernel, published on 11 Sep 2025. 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:

ACPI: APEI: send SIGBUS to current task if synchronous memory error not recovered

If a synchronous error is detected as a result of user-space process
triggering a 2-bit uncorrected error, the CPU will take a synchronous
error exception such as Synchronous External Abort (SEA) on Arm64. The
kernel will queue a memory_failure() work which poisons the related
page, unmaps the page, and then sends a SIGBUS to the process, so that
a system wide panic can be avoided.

However, no memory_failure() work will be queued when abnormal
synchronous errors occur. These errors can include situations like
invalid PA, unexpected severity, no memory failure config support,
invalid GUID section, etc. In such a case, the user-space process will
trigger SEA again.  This loop can potentially exceed the platform
firmware threshold or even trigger a kernel hard lockup, leading to a
system reboot.

Fix it by performing a force kill if no memory_failure() work is queued
for synchronous errors.

[ rjw: Changelog edits ]

## Which versions are affected by CVE-2025-39763?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-39763?

Apply the vendor's patch.

## Is CVE-2025-39763 being exploited?

There is no known exploitation of CVE-2025-39763 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-2025-39763 and fix it if it is affected.

What it is: CVE-2025-39763 is a medium-severity denial of service vulnerability in Linux kernel, published on 11 Sep 2025. 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-2025-39763 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-2025-39763/ (Markdown: https://insights.sbomify.com/CVE-2025-39763/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39763
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39763
- OSV: https://osv.dev/vulnerability/CVE-2025-39763

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-39763/
Summaries are generated and may contain mistakes; the official description above is the record.