CVE-2025-29951 Overview
CVE-2025-29951 is a stack-based buffer overflow [CWE-121] in the AMD Secure Processor (ASP) bootloader. The flaw lets an attacker with local, low-privileged access overwrite memory in the ASP bootloader execution context. Successful exploitation can lead to privilege escalation and arbitrary code execution within the secure processor environment. AMD documented the issue in AMD Security Bulletin SB-4013. Because the ASP is a root-of-trust component, code execution at this layer undermines platform isolation guarantees that downstream operating system defenses depend on.
Critical Impact
An attacker with local access can corrupt ASP bootloader memory and execute arbitrary code within the secure processor, breaking the platform root of trust.
Affected Products
- AMD Secure Processor (ASP) bootloader
- AMD platforms listed in AMD Security Bulletin SB-4013
- Systems relying on the ASP for secure boot and firmware attestation
Discovery Timeline
- 2026-02-10 - CVE-2025-29951 published to NVD
- 2026-04-15 - Last updated in NVD database
Technical Details for CVE-2025-29951
Vulnerability Analysis
The AMD Secure Processor is an ARM-based coprocessor embedded in AMD SoCs. It executes early-boot firmware before the x86 cores come out of reset and establishes the platform root of trust. The bootloader running on the ASP validates and loads subsequent firmware stages. A stack-based buffer overflow [CWE-121] in this bootloader allows an attacker to write past a fixed-size buffer and overwrite adjacent stack memory, including saved return addresses and control data.
Exploitation requires local access and low privileges on the host, and the attack complexity is high. The impact covers confidentiality, integrity, and availability of the ASP execution context. Compromise at this stage undermines secure boot, firmware Trusted Platform Module (fTPM) attestation, and any memory encryption keys derived inside the ASP.
Root Cause
The bootloader processes attacker-influenced input without enforcing length checks against the destination buffer. The unchecked copy lets oversized input overflow the stack frame and corrupt the saved return address or other control state used by the bootloader.
Attack Vector
The attack vector is local. An adversary with privileged access to firmware update interfaces or bootloader-controlled data structures supplies a malformed payload. When the ASP bootloader parses the payload, the overflow occurs and execution can be redirected into attacker-controlled memory. AMD has not published exploitation code, and no public proof of concept is available. Refer to AMD Security Bulletin SB-4013 for vendor technical detail.
Detection Methods for CVE-2025-29951
Indicators of Compromise
- Unexpected ASP firmware version strings or attestation measurements that do not match known-good values.
- Failed or anomalous secure boot logs and fTPM event log entries.
- Unscheduled BIOS or firmware updates initiated from user-mode tooling.
Detection Strategies
- Compare platform firmware measurements against vendor-published reference values using TPM/fTPM PCR attestation.
- Monitor for local privilege escalation chains that precede firmware flashing operations, since the attacker must reach the ASP interface from the host.
- Inspect vendor firmware update utilities for invocation by non-administrative or non-vendor processes.
Monitoring Recommendations
- Centralize firmware version inventory and alert on drift from approved baselines across the fleet.
- Track Windows and Linux kernel events related to /dev/sev, psp driver access, and BIOS update services.
- Forward platform attestation results to a SIEM and alert on unexpected PCR changes.
How to Mitigate CVE-2025-29951
Immediate Actions Required
- Inventory AMD-based systems and identify models listed in AMD Security Bulletin SB-4013.
- Apply the BIOS/UEFI update containing the fixed ASP bootloader from your OEM as soon as it is published for your platform.
- Restrict local administrative access and firmware update privileges to a minimal set of accounts.
Patch Information
AMD has released fixed ASP bootloader firmware delivered through OEM BIOS updates. Consult AMD Security Bulletin SB-4013 and your hardware vendor's support portal for the specific BIOS version that includes the fix for your platform.
Workarounds
- Enforce strong local access controls and full-disk encryption to raise the bar for an attacker reaching the ASP interface.
- Enable measured boot and remote attestation so that bootloader compromise is detectable even if exploitation succeeds.
- Disable unused firmware update mechanisms and require signed vendor capsules for any BIOS flashing operation.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
