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.
- 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-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 include Linux kernel.
How do I fix CVE-2025-21913?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
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
Sources
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.