CVE-2025-54505: AMD CPU Information Disclosure Vulnerability

CVE-2025-54505 Overview

A transient execution vulnerability has been identified within AMD CPUs that may allow a local user-privileged attacker to leak data via the floating point divisor unit. This side-channel attack targets the speculative execution behavior of AMD processors, potentially resulting in loss of confidentiality by allowing an attacker to extract sensitive information from memory that should otherwise be inaccessible.

Critical Impact

Local attackers with user-level privileges may exploit this transient execution flaw to leak sensitive data through the floating point divisor unit, compromising system confidentiality.

Affected Products

• AMD CPUs with floating point divisor units susceptible to transient execution side-channel attacks
• Systems running Xen hypervisor (see XSA-488)
• Various AMD processor families (refer to AMD Security Bulletin SB-7053 for complete list)

Discovery Timeline

• 2026-04-27 - CVE-2025-54505 published to NVD
• 2026-04-29 - Last updated in NVD database

Technical Details for CVE-2025-54505

Vulnerability Analysis

This vulnerability belongs to the class of transient execution attacks, similar to other well-known speculative execution vulnerabilities such as Spectre and Meltdown. The flaw specifically targets the floating point divisor unit within AMD processors, exploiting the speculative execution behavior that allows CPUs to execute instructions ahead of time for performance optimization.

During transient execution, the processor may speculatively perform floating point division operations before security checks are completed. While these speculative results are eventually discarded if the checks fail, the operations can leave observable microarchitectural side effects in the floating point divisor unit. A local attacker with user-level privileges can exploit these side effects to infer sensitive data that would normally be protected by hardware isolation mechanisms.

The attack requires local access and user-level privileges, limiting the attack surface compared to remotely exploitable vulnerabilities. However, in multi-tenant environments such as cloud computing platforms using virtualization (as addressed by Xen Advisory XSA-488), this vulnerability poses a more significant risk as attackers in one virtual machine could potentially extract data from other VMs or the hypervisor.

Root Cause

The root cause stems from the microarchitectural implementation of the floating point divisor unit in affected AMD processors. During speculative execution, the processor performs floating point division operations before determining whether the associated memory access is permitted. The side effects of these speculative operations persist in the microarchitectural state even after the speculative results are rolled back, creating a covert channel through which data can be leaked.

Attack Vector

The attack requires local access to the target system with user-level privileges. An attacker must be able to execute code on the same physical processor as the victim process. The exploitation involves:

1. Triggering speculative execution that causes the floating point divisor unit to process sensitive data
2. Measuring timing variations or other microarchitectural side effects in the floating point unit
3. Using these measurements to infer the values of data that was speculatively processed

The attack exploits the timing behavior of the floating point divisor, where different operand values result in measurably different execution times or microarchitectural states.

The vulnerability mechanism involves measuring side-channel signals from the floating point divisor unit during transient execution. For detailed technical analysis and proof-of-concept information, refer to the AMD Security Bulletin SB-7053 and Xen Advisory XSA-488.

Detection Methods for CVE-2025-54505

Indicators of Compromise

• Unusual patterns of floating point operations combined with memory access timing measurements
• Processes attempting to measure execution timing of floating point division operations
• Unexpected cache timing probes or performance counter access attempts
• Anomalous process behavior consistent with side-channel attack techniques

Detection Strategies

• Monitor for processes using high-precision timing mechanisms (e.g., rdtsc, rdtscp, performance counters) in combination with floating point operations
• Implement behavioral analysis to detect cache-timing attack patterns characteristic of transient execution exploits
• Deploy endpoint detection rules that identify known side-channel attack tooling or techniques

Monitoring Recommendations

• Enable detailed CPU performance monitoring on critical systems to detect anomalous floating point unit behavior
• Implement process-level auditing for suspicious use of timing-related system calls
• In virtualized environments, monitor for guest VMs exhibiting attack patterns against the hypervisor or other guests
• Consider deploying SentinelOne's behavioral AI engine to detect exploitation attempts through anomalous execution patterns

How to Mitigate CVE-2025-54505

Immediate Actions Required

• Review the AMD Security Bulletin SB-7053 for specific mitigation guidance for your processor family
• Apply microcode updates from AMD when available for affected processor models
• For Xen environments, review and apply guidance from Xen Advisory XSA-488
• Evaluate the risk in your environment based on the local access requirement and implement additional access controls as needed

Patch Information

AMD has published Security Bulletin SB-7053 addressing this vulnerability. System administrators should consult the bulletin for specific microcode updates and firmware patches applicable to their processor models. For systems using Xen hypervisor, Xen Advisory XSA-488 provides additional guidance on hypervisor-level mitigations.

Microcode and firmware updates should be applied through:

• BIOS/UEFI updates from system vendors
• Operating system microcode loading mechanisms
• Hypervisor updates for virtualized environments

Workarounds

• Restrict local access to systems processing sensitive data to reduce the attack surface
• In multi-tenant environments, consider processor affinity controls to limit co-residency of sensitive workloads
• Implement kernel-level mitigations that reduce the precision of timing measurements available to user-space processes
• Consider enabling existing transient execution mitigations in the operating system and hypervisor

# Example: Check for AMD microcode version on Linux
cat /proc/cpuinfo | grep -i microcode

# Example: Verify Xen hypervisor version for XSA-488 patch status
xl info | grep xen_version