Guest timekeeping disruption via nominal TSC frequency
Published Aug 16, 2025 · Updated Aug 5, 2026
Improper time calculation in Linux 6.14 through 6.15.6 allows local users to disrupt SEV-SNP guest timekeeping via Secure TSC. The x86/sev early TSC initialization path derives GUEST_TSC_FREQ from nominal P0 frequency instead of the firmware secrets-page TSC_FACTOR, so a small frequency error accumulates into clock skew and early hrtimer expiry. Exposure requires an SEV-SNP guest with Secure TSC enabled, a deployment condition the attacker cannot invoke or influence, and the documented consequence is inaccurate guest time rather than data access or modification.
Summary
What happened
Improper time calculation in Linux 6.14 through 6.15.6 allows local users to disrupt SEV-SNP guest timekeeping via Secure TSC. The x86/sev early TSC initialization path derives GUEST_TSC_FREQ from nominal P0 frequency instead of the firmware secrets-page TSC_FACTOR, so a small frequency error accumulates into clock skew and early hrtimer expiry. Exposure requires an SEV-SNP guest with Secure TSC enabled, a deployment condition the attacker cannot invoke or influence, and the documented consequence is inaccurate guest time rather than data access or modification.
The record
- CVE
- CVE-2025-38508
- Published
- Aug 16, 2025
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Aug 16, 2025CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=6.14
- Affected versionversion=73bbf3b0fbba9aa27fef07a1fbd837661a863f03 <52e1a03e6cf61ae165f59f41c44394a653a0a788
- Affected versionversion=73bbf3b0fbba9aa27fef07a1fbd837661a863f03 <d0195c42e65805938c9eb507657e7cdf8e1e9522
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What is affected?
Published CVSS scores
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Attacks
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Technologies
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