CVE-2025-21913
Linux Kernel 6.1 – 6.1.131
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HSummary
CVE-2025-21913 is a medium-severity an unspecified weakness vulnerability in Linux Linux Kernel. Its CVSS base score is 5.5 (Medium).
Operationally, ranked at the 9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-11 (Error Handling) and SC-39 (Process Isolation) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-9408
Vulnerability Data
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…
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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.
- CWE(s)
Related Threats
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Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly requires proper error handling for operations such as the unsafe RDMSR on MSR_FAM10H_MMIO_CONF_BASE that triggers the Xen unchecked access warning.
Enforces process/kernel isolation boundaries so that low-level MSR accesses for MMCONFIG discovery remain contained and do not produce hypervisor-visible faults.
Provides memory and register protection mechanisms that can limit the impact of erroneous model-specific register reads in kernel code paths.