Local write-protection bypass via lost UFFD flag
Published Aug 15, 2026 · Updated Aug 15, 2026
Improper permission preservation in Linux 6.19 allows local users to bypass UFFD write protection on device-private huge pages. The change_non_present_huge_pmd() path rewrites a writable device-private PMD swap entry as readable without copying its pmd_swp_uffd_wp bit, so swap-in misses the expected trap. Reachability requires local low-privileged access, a UFFD_WP-marked device-private transparent huge page, and an mprotect() downgrade; the bounded result is loss of the intended write-protection trap.
Summary
What happened
Improper permission preservation in Linux 6.19 allows local users to bypass UFFD write protection on device-private huge pages. The change_non_present_huge_pmd() path rewrites a writable device-private PMD swap entry as readable without copying its pmd_swp_uffd_wp bit, so swap-in misses the expected trap. Reachability requires local low-privileged access, a UFFD_WP-marked device-private transparent huge page, and an mprotect() downgrade; the bounded result is loss of the intended write-protection trap.
The record
- CVE
- CVE-2026-72180
- Published
- Aug 15, 2026
- Updated
- Aug 15, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-281
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 15, 2026CVE publishedPublication date reported by the CVE source.
- Aug 15, 2026Record updatedLatest update available in the CVE record.
Exploitability
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Is a vulnerable build present?
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- Affected versionversion=368076f52ebeecd33e10a9f80905d7508b6b6149 <2611f7521c6c124b1bef1be4fc319e0ca144502f
- Affected versionversion=368076f52ebeecd33e10a9f80905d7508b6b6149 <f7e2c21bd1f57cd5350eecdfdb5d6025ca6afbab
- Affected versionversion=6.19
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What is affected?
Published CVSS scores
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Attacks
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Technologies
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