CVE-2025-48517 Overview
CVE-2025-48517 is an Insufficient Granularity of Access Control vulnerability in AMD Secure Encrypted Virtualization (SEV) firmware. This firmware-level security flaw could allow a privileged user operating a malicious hypervisor to create a SEV-ES (Encrypted State) guest with an Address Space Identifier (ASID) in the range reserved for SEV-SNP (Secure Nested Paging) guests, potentially resulting in a partial loss of confidentiality for affected virtual machine workloads.
Critical Impact
A privileged attacker with hypervisor access could exploit improper ASID range enforcement to compromise the confidentiality boundaries between SEV-ES and SEV-SNP guest environments.
Affected Products
- AMD SEV Firmware (specific versions not disclosed)
- AMD processors with SEV-ES and SEV-SNP capabilities
- Hypervisor environments utilizing AMD SEV technology
Discovery Timeline
- 2026-02-10 - CVE CVE-2025-48517 published to NVD
- 2026-02-10 - Last updated in NVD database
Technical Details for CVE-2025-48517
Vulnerability Analysis
This vulnerability stems from insufficient access control granularity within the AMD SEV firmware's ASID management system. AMD SEV technology provides hardware-based memory encryption for virtual machines, with different security levels offered through SEV-ES and SEV-SNP implementations. SEV-SNP represents a more advanced security model with additional integrity protections beyond what SEV-ES provides.
The firmware fails to properly enforce separation between the ASID ranges designated for SEV-ES and SEV-SNP guests. This architectural weakness allows a privileged attacker controlling the hypervisor to manipulate guest creation parameters, enabling the instantiation of a SEV-ES guest using an ASID that should be exclusively reserved for SEV-SNP guests.
The attack requires local access and high privileges (hypervisor-level control), which limits the attack surface but presents significant risk in multi-tenant cloud environments where hypervisor compromise could affect multiple customers. The exploitation does not require user interaction and maintains a low attack complexity once the attacker has achieved the necessary privilege level.
Root Cause
The root cause is classified as CWE-1220: Insufficient Granularity of Access Control. The SEV firmware does not implement sufficiently fine-grained checks to validate that ASID allocations for SEV-ES guests remain within their designated range and do not overlap with ASIDs reserved for the more secure SEV-SNP guest type. This boundary enforcement failure at the firmware level allows the security domain separation to be violated.
Attack Vector
The attack vector is local, requiring an attacker to have compromised or control the hypervisor layer. From this privileged position, the attacker can manipulate SEV guest creation API calls to specify ASID values that should be prohibited for SEV-ES guests. The firmware's inadequate validation allows these malformed requests to succeed, creating a SEV-ES guest that operates within what the system considers SEV-SNP address space.
This manipulation could potentially allow the attacker to bypass certain security checks that rely on ASID-based differentiation between guest types, leading to information leakage scenarios where confidential data from SEV-SNP protected workloads becomes partially accessible.
The vulnerability mechanism involves the firmware's ASID allocation and validation routines failing to enforce proper boundaries between guest security levels. For detailed technical information, refer to the AMD Security Bulletin SB-3023.
Detection Methods for CVE-2025-48517
Indicators of Compromise
- Unusual ASID allocation patterns in SEV guest creation logs
- SEV-ES guests operating with ASID values outside the expected range
- Anomalous hypervisor behavior during guest VM instantiation
- Unexpected access patterns to memory regions protected by SEV-SNP
Detection Strategies
- Monitor hypervisor-level SEV API calls for abnormal ASID parameters during guest creation
- Implement audit logging for all SEV guest instantiation events with ASID tracking
- Deploy firmware integrity verification to detect unauthorized SEV firmware modifications
- Utilize host-based intrusion detection systems to identify suspicious hypervisor activities
Monitoring Recommendations
- Enable verbose logging for AMD SEV firmware operations where supported
- Implement alerting for SEV guest creation events with ASID values in SNP-reserved ranges
- Regularly audit hypervisor configuration and access controls
- Monitor for unauthorized privilege escalation attempts targeting hypervisor components
How to Mitigate CVE-2025-48517
Immediate Actions Required
- Review AMD Security Bulletin SB-3023 for applicable firmware updates
- Assess exposure by identifying systems utilizing AMD SEV-ES and SEV-SNP features
- Implement strict access controls for hypervisor management interfaces
- Consider temporarily disabling SEV-ES guest creation in high-security environments until patching is complete
Patch Information
AMD has released a security bulletin addressing this vulnerability. System administrators should consult the AMD Security Bulletin SB-3023 for detailed patching guidance and updated SEV firmware versions. Firmware updates should be applied following vendor-recommended procedures, which may require system downtime and BIOS/UEFI updates.
Workarounds
- Restrict hypervisor administrative access to trusted personnel only
- Implement network segmentation to isolate hypervisor management interfaces
- Enable additional monitoring and alerting for SEV guest creation activities
- Consider hardware security modules (HSM) for additional hypervisor integrity verification
- Review and harden hypervisor configurations per vendor security guidelines
# Example: Verify current SEV firmware status (AMD platform-specific)
# Consult your platform vendor for exact commands
dmesg | grep -i "sev"
cat /sys/module/kvm_amd/parameters/sev
cat /sys/module/kvm_amd/parameters/sev_es
cat /sys/module/kvm_amd/parameters/sev_snp
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
