# CVE-2025-21913: x86/amd_nb: Use rdmsr_safe() in amd_get_mmconfig_range()

> A missing safe MSR access check in the Linux kernel causes a warning and potential instability on AMD systems running under Xen.

- **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:** 1 Apr 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2025-21913, DEBIAN-CVE-2025-21913, GHSA-2qpc-wrp3-2p98, ROOT-OS-UBUNTU-2404-CVE-2025-21913, UBUNTU-CVE-2025-21913

## What is CVE-2025-21913?

CVE-2025-21913 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Apr 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:

x86/amd_nb: Use rdmsr_safe() in amd_get_mmconfig_range()

Xen doesn't offer MSR_FAM10H_MMIO_CONF_BASE to all guests.  This results
in the following warning:

  unchecked MSR access error: RDMSR from 0xc0010058 at rIP: 0xffffffff8101d19f (xen_do_read_msr+0x7f/0xa0)
  Call Trace:
   xen_read_msr+0x1e/0x30
   amd_get_mmconfig_range+0x2b/0x80
   quirk_amd_mmconfig_area+0x28/0x100
   pnp_fixup_device+0x39/0x50
   __pnp_add_device+0xf/0x150
   pnp_add_device+0x3d/0x100
   pnpacpi_add_device_handler+0x1f9/0x280
   acpi_ns_get_device_callback+0x104/0x1c0
   acpi_ns_walk_namespace+0x1d0/0x260
   acpi_get_devices+0x8a/0xb0
   pnpacpi_init+0x50/0x80
   do_one_initcall+0x46/0x2e0
   kernel_init_freeable+0x1da/0x2f0
   kernel_init+0x16/0x1b0
   ret_from_fork+0x30/0x50
   ret_from_fork_asm+0x1b/0x30

based on quirks for a "PNP0c01" device.  Treating MMCFG as disabled is the
right course of action, so no change is needed there.

This was most likely exposed by fixing the Xen MSR accessors to not be
silently-safe.

## Which versions are affected by CVE-2025-21913?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-21913?

Apply the vendor's patch.

## Is CVE-2025-21913 being exploited?

There is no known exploitation of CVE-2025-21913 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-2025-21913 and fix it if it is affected.

What it is: CVE-2025-21913 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Apr 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-2025-21913 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-2025-21913/ (Markdown: https://insights.sbomify.com/CVE-2025-21913/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-21913
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-21913
- OSV: https://osv.dev/vulnerability/CVE-2025-21913

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-21913/
Summaries are generated and may contain mistakes; the official description above is the record.