Pre-OS code execution via unenforced SBAT revocation
Published Jun 9, 2026 · Updated Jun 9, 2026
Secure Boot bypass in Microsoft-signed UEFI shim bootloaders allows local users with administrative access to run code before OS startup. The legacy bootloaders lack effective Secure Boot Advanced Targeting enforcement, so firmware accepts their signatures despite applicable revocation data. Administrative access or equivalent control of the boot process is required; successful use bypasses Secure Boot and executes arbitrary code before OS defenses load.
Summary
What happened
Secure Boot bypass in Microsoft-signed UEFI shim bootloaders allows local users with administrative access to run code before OS startup. The legacy bootloaders lack effective Secure Boot Advanced Targeting enforcement, so firmware accepts their signatures despite applicable revocation data. Administrative access or equivalent control of the boot process is required; successful use bypasses Secure Boot and executes arbitrary code before OS defenses load.
The record
- CVE
- CVE-2026-8863
- Published
- Jun 9, 2026
- Updated
- Jun 9, 2026
- Vendor
- NTC IT ROSA
- Product
- ROSA Linux
- Classifications
- CWE-1329, T1542.003
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Jun 9, 2026CVE publishedPublication date reported by the CVE source.
- Jun 9, 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=R10
- Affected versionversion=R9
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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