Boot-phase information disclosure via unchecked section entry
Published Jan 29, 2024 · Updated Jan 27, 2026
An out-of-bounds read in shim on affected Red Hat Enterprise Linux systems allows local users to disclose boot-phase memory. In verify_buffer_sbat(), a goal-seeking loop compares a PE section name with .sbat before confirming that the section-table entry lies inside the supplied binary. Exploitation requires low-privileged local access and a crafted EFI binary in the boot path; the documented consequence is memory disclosure, while broader exploitation remains unconfirmed.
Summary
What happened
An out-of-bounds read in shim on affected Red Hat Enterprise Linux systems allows local users to disclose boot-phase memory. In verify_buffer_sbat(), a goal-seeking loop compares a PE section name with .sbat before confirming that the section-table entry lies inside the supplied binary. Exploitation requires low-privileged local access and a crafted EFI binary in the boot path; the documented consequence is memory disclosure, while broader exploitation remains unconfirmed.
The record
- CVE
- CVE-2023-40550
- Published
- Jan 29, 2024
- Updated
- Jan 27, 2026
- Vendor
- Red Hat
- Product
- Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
- Classifications
- CWE-125
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 29, 2024CVE publishedPublication date reported by the CVE source.
- Jan 27, 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?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
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
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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