CVE-2025-29952: AMD SEV Firmware Privilege Escalation Flaw

CVE-2025-29952 Overview

CVE-2025-29952 is an improper initialization vulnerability [CWE-457] in AMD Secure Encrypted Virtualization (SEV) firmware. An attacker with administrative privileges on the host can corrupt memory covered by the Reverse Map Table (RMP), undermining guest memory integrity. The flaw affects confidential computing workloads that rely on SEV-SNP to isolate guest virtual machines from a compromised hypervisor or host administrator.

Critical Impact
An admin-privileged local attacker can corrupt RMP-covered memory, breaking the integrity guarantees that SEV provides to confidential guest VMs.

Affected Products

AMD processors implementing Secure Encrypted Virtualization (SEV) firmware
AMD EPYC server platforms using SEV-SNP for confidential virtual machines
Refer to the AMD Security Bulletin AMD-SB-3023 for the authoritative list of affected SKUs and firmware versions

Discovery Timeline

2026-02-10 - CVE-2025-29952 published to NVD
2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-29952

Vulnerability Analysis

The vulnerability resides in AMD SEV firmware, which manages the cryptographic isolation of guest VMs on AMD EPYC platforms. SEV-SNP uses a Reverse Map Table (RMP) to track ownership and permissions for every system page that backs a confidential guest. The RMP is the authoritative structure the processor consults to enforce guest memory integrity against a malicious or compromised hypervisor.

Because the firmware fails to fully initialize internal state before operating on RMP-protected pages, an admin-privileged actor on the host can drive the firmware into operations that corrupt those pages. The result is a loss of guest memory integrity, which violates the core security promise of SEV-SNP. Exploitation requires local access and high privileges on the host platform, and there is no impact on confidentiality or availability of the host itself.

Root Cause

The root cause is improper initialization [CWE-457] within the SEV firmware. One or more variables, structures, or state fields are used before being set to a known-safe value. When the firmware subsequently acts on RMP-covered memory, the uninitialized state allows attacker-influenced operations to alter contents that the RMP is supposed to protect.

Attack Vector

The attack vector is local and requires high privileges on the host. An attacker who already controls the host administrator role, such as a malicious cloud operator or an attacker who has compromised the hypervisor management plane, invokes SEV firmware interfaces in a sequence that exercises the uninitialized state. No user interaction is required. The attacker cannot mount this attack from inside a guest VM or remotely over the network.

No public proof-of-concept code is available. Technical specifics are limited to the description provided by AMD in security bulletin AMD-SB-3023.

Detection Methods for CVE-2025-29952

Indicators of Compromise

No specific file hashes, network indicators, or host artifacts have been published for this firmware-level issue.
Unexpected SEV firmware command sequences issued by the host or hypervisor management stack outside of normal VM lifecycle operations.
Guest VM integrity failures, attestation mismatches, or SNP_GUEST_REQUEST errors reported by confidential workloads.

Detection Strategies

Inventory AMD EPYC hosts and compare installed SEV firmware versions against the fixed versions listed in AMD-SB-3023.
Monitor hypervisor logs for anomalous use of SEV platform commands such as SNP_PAGE_MOVE, SNP_PAGE_SET_PRIVATE, or RMP update operations by non-standard processes.
Correlate host administrator activity with SEV firmware interactions to surface privileged operations that deviate from established baselines.

Monitoring Recommendations

Collect hypervisor and kernel logs covering KVM SEV ioctls and forward them to a centralized analytics platform for baseline analysis.
Track guest attestation reports continuously and alert when measurements change unexpectedly between boots.
Audit privileged account use on virtualization hosts and flag interactive sessions that touch SEV management interfaces.

How to Mitigate CVE-2025-29952

Immediate Actions Required

Apply the SEV firmware update referenced in AMD Security Bulletin AMD-SB-3023 to every affected AMD EPYC host.
Restrict host administrator access to the minimum number of accounts and enforce multi-factor authentication for all privileged virtualization roles.
Re-attest confidential guest VMs after patching to confirm that integrity measurements match expected values.

Patch Information

AMD has released updated SEV firmware as documented in security bulletin AMD-SB-3023. Coordinate firmware deployment with the platform vendor or cloud provider responsible for the BIOS and PSP firmware bundle, since SEV firmware is typically distributed inside platform firmware updates rather than as a standalone package.

Workarounds

No vendor-supplied workaround replaces the firmware update; patching is the only complete remediation.
Tightly control which administrators can issue SEV platform commands and segregate hypervisor management networks from general administrative networks.
Treat SEV-SNP attestation as mandatory for sensitive guests so that integrity violations are surfaced to workload owners rather than relying solely on host trust.

bash

# Verify the SEV firmware version reported by the platform on a Linux host
cat /sys/module/ccp/parameters/psp_firmware_version 2>/dev/null || \
  dmesg | grep -i 'sev api'

# Confirm SEV-SNP is enabled and check supported features
dmesg | grep -iE 'sev|snp'