CVE-2025-58773: AMI APTIO BIOS Buffer Overflow Vulnerability

CVE-2025-58773 Overview

CVE-2025-58773 is an out-of-bounds write vulnerability [CWE-787] in AMI APTIOV BIOS firmware. The flaw allows a local attacker with high privileges to write data outside the bounds of allocated memory. Successful exploitation can trigger buffer overflows, memory corruption, and arbitrary code execution within the BIOS context. Because the vulnerability resides in platform firmware, successful attacks can compromise the confidentiality, integrity, and availability of the host system.

Critical Impact
Local exploitation of this AMI APTIOV BIOS flaw can lead to arbitrary code execution at the firmware level, bypassing operating system protections and persisting below the OS boundary.

Affected Products

AMI APTIOV BIOS firmware (see AMI Security Advisory 2026002 for affected versions)
Platforms shipping with vulnerable AMI APTIOV BIOS builds
Server, workstation, and embedded systems using AMI UEFI reference firmware

Discovery Timeline

2026-10-13 - CVE-2025-58773 published to the National Vulnerability Database
2026-10-15 - Entry last modified in NVD

Technical Details for CVE-2025-58773

Vulnerability Analysis

The vulnerability is categorized as an out-of-bounds write [CWE-787] in the AMI APTIOV BIOS. During processing of attacker-influenced input, the firmware writes data past the end of an allocated buffer. This write corrupts adjacent memory structures used by System Management Mode (SMM) or Driver Execution Environment (DXE) components. An attacker who controls the overwritten memory can redirect execution flow inside the firmware runtime.

Because BIOS code runs before and alongside the operating system kernel, successful exploitation grants execution at a privilege level above the OS. This allows an adversary to disable security features, implant persistent firmware payloads, or stage bootkits. The vulnerability requires local access and high privileges, which limits remote mass exploitation but makes it attractive for post-compromise persistence.

Root Cause

The root cause is improper validation of buffer boundaries when the APTIOV BIOS processes certain input data. The firmware fails to verify that write operations stay within the allocated memory region. AMI's advisory describes the condition as an out-of-bounds write reachable through local access, consistent with CWE-787.

Attack Vector

Exploitation requires local access to the target system and high-level privileges, typically administrative or root rights on the running operating system. From that context, an attacker interacts with firmware interfaces such as SMI handlers, UEFI runtime services, or variable services to trigger the vulnerable code path. User interaction is not required. The high attack complexity reflects the firmware-specific conditions needed to reach and exploit the vulnerable routine.

No public proof-of-concept exploit is listed in the enriched data, and the vulnerability is not present on the CISA Known Exploited Vulnerabilities list.

Detection Methods for CVE-2025-58773

Indicators of Compromise

Unexpected changes to UEFI variables or boot order entries following administrative sessions on affected hosts.
Firmware measurements or TPM PCR values that deviate from a known-good baseline after reboot.
SMM or DXE driver crashes, machine-check exceptions, or unexplained bugchecks reported through platform event logs.

Detection Strategies

Compare installed BIOS versions against the fixed releases listed in AMI Security Advisory 2026002 across the fleet.
Use firmware integrity tooling such as CHIPSEC to detect anomalous SMRAM contents or protected region modifications.
Correlate local privilege escalation events with subsequent firmware-related interactions to identify suspicious sequences.

Monitoring Recommendations

Enable and forward UEFI Secure Boot, measured boot, and platform event log telemetry to a central analytics platform.
Monitor administrative-session telemetry for execution of firmware update utilities or SMI-triggering tooling by non-authorized accounts.
Track BIOS version inventory continuously and alert when hosts remain on vulnerable builds past the remediation window.

How to Mitigate CVE-2025-58773

Immediate Actions Required

Identify all systems running AMI APTIOV BIOS and inventory current firmware versions.
Restrict administrative and physical access to affected systems, since exploitation requires high local privileges.
Apply the firmware update supplied by the system OEM once it incorporates the AMI fix for CVE-2025-58773.

Patch Information

AMI has published remediation guidance in AMI Security Advisory 2026002. Firmware fixes are delivered through downstream OEM BIOS updates. Consult your hardware vendor's security advisories for the specific BIOS version that incorporates the AMI patch for your platform, and schedule updates through a validated firmware deployment process.

Workarounds

Enforce least privilege so that only approved administrators can execute firmware management utilities on affected hosts.
Enable UEFI Secure Boot, BIOS administrator passwords, and chassis intrusion protections to raise the cost of local exploitation.
Isolate high-value systems in segmented management networks until vendor BIOS updates can be validated and deployed.

bash

# Example: inventory BIOS vendor and version on Linux hosts for triage
sudo dmidecode -s bios-vendor
sudo dmidecode -s bios-version
sudo dmidecode -s bios-release-date