False KMSAN alert via undersized store instrumentation
Published Jan 5, 2026 · Updated Jan 5, 2026
False-positive KMSAN reporting in affected Linux Kernel builds allows local users running ping to trigger an uninitialized-value alert. The s390 fpu_vstl() inline assembly can write more than one byte when index is positive, but Clang instruments only a one-byte store from compile-time constraints. Reachability requires an s390 kernel built with KMSAN and the relevant ping path; the result is a spurious diagnostic rather than data exposure, memory corruption, or service interruption.
Summary
What happened
False-positive KMSAN reporting in affected Linux Kernel builds allows local users running ping to trigger an uninitialized-value alert. The s390 fpu_vstl() inline assembly can write more than one byte when index is positive, but Clang instruments only a one-byte store from compile-time constraints. Reachability requires an s390 kernel built with KMSAN and the relevant ping path; the result is a spurious diagnostic rather than data exposure, memory corruption, or service interruption.
The record
- CVE
- CVE-2025-68751
- Published
- Jan 5, 2026
- Updated
- Jan 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- Unavailable
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Jan 5, 2026CVE publishedPublication date reported by the CVE source.
- Jan 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=6.9
- Affected versionversion=dcd3e1de9d17dc43dfed87a9fc814b9dec508043 <13dcd6308cb8f67134ee5d5d762b2a66363c695b
- Affected versionversion=dcd3e1de9d17dc43dfed87a9fc814b9dec508043 <14e4e4175b64dd9216b522f6ece8af6997d063b2
- Affected versionversion=dcd3e1de9d17dc43dfed87a9fc814b9dec508043 <946357a538bb47740635c25520924351d2d91544
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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Your stack
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