Code execution via HTTP response out-of-bounds write
Published Jan 25, 2024 · Updated Jun 26, 2026
Out-of-bounds write in Shim HTTP boot support in Red Hat Enterprise Linux allows man-in-the-middle attackers to execute code. The httpboot.c response parser trusts attacker-controlled HTTP values and uses them in memory operations, yielding a controlled out-of-bounds write. Exploitation requires UEFI HTTP network boot during early startup plus interception of boot traffic or control of the configured boot server.
Summary
What happened
Out-of-bounds write in Shim HTTP boot support in Red Hat Enterprise Linux allows man-in-the-middle attackers to execute code. The httpboot.c response parser trusts attacker-controlled HTTP values and uses them in memory operations, yielding a controlled out-of-bounds write. Exploitation requires UEFI HTTP network boot during early startup plus interception of boot traffic or control of the configured boot server.
The record
- CVE
- CVE-2023-40547
- Published
- Jan 25, 2024
- Updated
- Jun 26, 2026
- Vendor
- Red Hat
- Product
- Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
- Classifications
- CWE-787, T1557, T1203
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 25, 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?
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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