Privilege escalation via inverted bitmap validation
Published Aug 11, 2026 · Updated Aug 11, 2026
Incorrect comparison in Intel TDX Guest software before 0.3.1 allows local users with high privileges to escalate privilege. The invalidate_l2_cached_ept function treats a zero or out-of-range L2 VM bitmap as valid because its mask comparison is inverted, then submits it through TDG.VP.INVEPT. Exploitation requires privileged Ring 3 access inside a TDX guest and no user interaction, allowing invalid L2 VM selections to bypass the library's input guard.
Summary
What happened
Incorrect comparison in Intel TDX Guest software before 0.3.1 allows local users with high privileges to escalate privilege. The invalidate_l2_cached_ept function treats a zero or out-of-range L2 VM bitmap as valid because its mask comparison is inverted, then submits it through TDG.VP.INVEPT. Exploitation requires privileged Ring 3 access inside a TDX guest and no user interaction, allowing invalid L2 VM selections to bypass the library's input guard.
The record
- CVE
- CVE-2026-20765
- Published
- Aug 11, 2026
- Updated
- Aug 11, 2026
- Vendor
- Topcon Positioning Systems, Inc.
- Product
- Intel TDX Guest software
- Classifications
- CWE-697, T1068
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Aug 11, 2026CVE publishedPublication date reported by the CVE source.
- Aug 11, 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?
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- Affected versionversion=before version 0.3.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
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Your stack
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