Secure Processor code execution via unlocked NBIO registers
Published May 13, 2026 · Updated May 13, 2026
Missing lock-bit protection in NBIO registers on affected AMD EPYC processors allows local administrators to access the SMN. The NBIO controls fail to lock FASTREG mappings, so a privileged host can remap MMIO and induce PSP writes into security-sensitive SMN controls. Host administrator access and an SEV-SNP guest are required; exploitation executes code in the ASP and permits reading or altering guest state.
Summary
What happened
Missing lock-bit protection in NBIO registers on affected AMD EPYC processors allows local administrators to access the SMN. The NBIO controls fail to lock FASTREG mappings, so a privileged host can remap MMIO and induce PSP writes into security-sensitive SMN controls. Host administrator access and an SEV-SNP guest are required; exploitation executes code in the ASP and permits reading or altering guest state.
The record
- CVE
- CVE-2025-61972
- Published
- May 13, 2026
- Updated
- May 13, 2026
- Vendor
- Advanced Micro Devices, Inc.
- Product
- AMD EPYC Embedded 8004 Series Processors
- Classifications
- CWE-1233, T1068
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- May 13, 2026CVE publishedPublication date reported by the CVE source.
- May 13, 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
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
- BreakFAST Linux host-kernel proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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