Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
Linux Linux — x86/sev: Use TSC_FACTOR for Secure TSC frequency calculation
AV AC PR UI S C I A CVSS EPSS %ile KEV
L L L N U N N H 5.5 .0013 2.8 —
AFFECTED
Product Versions Fixed
Linux 73bbf3b0fbba9aa27fef07a1fbd837661a863f03 – —
Linux 6.14 – 6.15.7
TIMELINE
Apr 16 Reserved by Linux
Aug 16 Published (CNA: Linux)
Jul 30 RESCORED — CVE-2025-38508 (Linux). CVSS 7.3 → 5.5 (NVD).
Description
In the Linux kernel, the following vulnerability has been resolved:
x86/sev: Use TSC_FACTOR for Secure TSC frequency calculation
When using Secure TSC, the GUEST_TSC_FREQ MSR reports a frequency based on
the nominal P0 frequency, which deviates slightly (typically ~0.2%) from
the actual mean TSC frequency due to clocking parameters.
Over extended VM uptime, this discrepancy accumulates, causing clock skew
between the hypervisor and a SEV-SNP VM, leading to early timer interrupts as
perceived by the guest.
The guest kernel relies on the reported nominal frequency for TSC-based
timekeeping, while the actual frequency set during SNP_LAUNCH_START may
differ. This mismatch results in inaccurate time calculations, causing the
guest to perceive hrtimers as firing earlier than expected.
Utilize the TSC_FACTOR from the SEV firmware's secrets page (see "Secrets
Page Format" in the SNP Firmware ABI Specification) to calculate the mean
TSC frequency, ensuring accurate timekeeping and mitigating clock skew in
SEV-SNP VMs.
Use early_ioremap_encrypted() to map the secrets page as
ioremap_encrypted() uses kmalloc() which is not available during early TSC
initialization and causes a panic.
[ bp: Drop the silly dummy var:
https://lore.kernel.org/r/20250630192726.GBaGLlHl84xIopx4Pt@fat_crate.local ]
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
| April 16, 2025 | Reserved | Reserved by Linux |
| August 16, 2025 | Published | Published (CNA: Linux) |
| July 30, 2026 | RESCORED | RESCORED — CVE-2025-38508 (Linux). CVSS 7.3 → 5.5 (NVD). |
Affected
Affected products and packages — 2 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
| Linux | Linux | — | 73bbf3b0fbba9aa27fef07a1fbd837661a863f03 | — |
| Linux | Linux | — | 6.14 | 6.15.7 |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2025-38508 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.