Boot-time memory corruption via unchecked SBAT size addition
Published Jan 29, 2024 · Updated Jun 26, 2026
Heap-based buffer overflow in shim on Red Hat Enterprise Linux allows local users to corrupt memory or crash 32-bit systems during UEFI boot. In verify_sbat_section, an unchecked addition to a user-controlled PE section size wraps before AllocatePool, while the subsequent copy uses the original size. Exploitation requires a 32-bit shim build and control of a PE binary loaded during boot, with consequences limited to memory corruption, a boot-time crash, or data-integrity loss.
Summary
What happened
Heap-based buffer overflow in shim on Red Hat Enterprise Linux allows local users to corrupt memory or crash 32-bit systems during UEFI boot. In verify_sbat_section, an unchecked addition to a user-controlled PE section size wraps before AllocatePool, while the subsequent copy uses the original size. Exploitation requires a 32-bit shim build and control of a PE binary loaded during boot, with consequences limited to memory corruption, a boot-time crash, or data-integrity loss.
The record
- CVE
- CVE-2023-40548
- Published
- Jan 29, 2024
- Updated
- Jun 26, 2026
- Vendor
- Red Hat
- Product
- Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
- Classifications
- CWE-190, CWE-787
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 29, 2024CVE publishedPublication date reported by the CVE source.
- Jun 26, 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
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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