boxscore/security
CVE · referencelatest edition

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.

CVE-2025-38508MEDIUM
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).
CNA: Linux · CVSS v3.1 · 2 references · NVD status: Modified

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
DateEventDetail
April 16, 2025ReservedReserved by Linux
August 16, 2025PublishedPublished (CNA: Linux)
July 30, 2026RESCOREDRESCORED — CVE-2025-38508 (Linux). CVSS 7.3 → 5.5 (NVD).

Affected

Affected products and packages — 2 rows
VendorProduct / PackageEcosystemVersion introducedFixed
LinuxLinux73bbf3b0fbba9aa27fef07a1fbd837661a863f03
LinuxLinux6.146.15.7

References (2)

Related

Authoritative record: CVE-2025-38508 at cve.org

Vendors: linux

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.