Remote code execution via negative file-handle length
Published May 16, 2022 · Updated Nov 3, 2025
Buffer overflow in Das U-Boot 2022.04 and earlier and 2022.07-rc1 through 2022.07-rc2 allows remote attackers to execute code via NFS. In nfs_lookup_reply, a network-derived NFSv3 file-handle length is stored as a signed integer, so a negative value bypasses the upper-bound check and becomes a huge memcpy size into the 64-byte filefh buffer. Exposure requires U-Boot networking with an NFS boot flow and an attacker on the same network or controlling the NFS server; successful exploitation gains bootloader-stage code execution before verified-boot signature checks.
Summary
What happened
Buffer overflow in Das U-Boot 2022.04 and earlier and 2022.07-rc1 through 2022.07-rc2 allows remote attackers to execute code via NFS. In nfs_lookup_reply, a network-derived NFSv3 file-handle length is stored as a signed integer, so a negative value bypasses the upper-bound check and becomes a huge memcpy size into the 64-byte filefh buffer. Exposure requires U-Boot networking with an NFS boot flow and an attacker on the same network or controlling the NFS server; successful exploitation gains bootloader-stage code execution before verified-boot signature checks.
The record
- CVE
- CVE-2022-30767
- Published
- May 16, 2022
- Updated
- Nov 3, 2025
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-120, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 16, 2022CVE publishedPublication date reported by the CVE source.
- Nov 3, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
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
- GitHub Security Lab U-Boot NFS RCE analysisproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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