AmpereOne Firmware CVE-2025-62864
CRITICALAttack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessGain OS kernel-level execution on host
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DeliveryCraft malformed MMCommunicate SMC call
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ExploitTrigger out-of-bounds write in UEFI-MM
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ExecutionCorrupt Secure Partition memory context
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ImpactEscalate into secure firmware / persist below OS
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, write limits
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires issuing an SMC (Secure Monitor Call) to the UEFI-MM MMCommunicate service, which in practice means the attacker must already be running privileged code on the host - typically OS kernel / EL1 level - on an affected AmpereOne platform (AC03 before 3.5.9.3, AC04 before 4.4.5.2, or AmpereOne M before 5.4.5.1). The limiting factor is this prerequisite privileged local execution context: despite the AV:N/PR:N rating, the MMCommunicate SMC interface is not reachable from a remote network position, so the flaw is gated behind prior compromise of the operating system. No special non-default configuration is indicated by the description; firmware below the listed fixed versions is affected as shipped. |
| Impact | The input CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N, C:H/I:H/A:H, base 9.8) rates this as critical and remotely exploitable without authentication, but that rating conflicts with the technical nature of the flaw. The vulnerability is triggered by 'an incorrectly formed SMC call to UEFI-MM MMCommunicate' - an SMC (Secure Monitor Call) is a privileged processor instruction issued by software already running on the host (typically the OS kernel/EL1), not a packet arriving over a network. This strongly implies the realistic attack vector is local and privileged rather than network/unauthenticated, so AV:N/PR:N likely overstate the exposure - verify the delivery path with Ampere. Exploitation status: no KEV listing and no POC referenced in the provided data, so there is no public exploit identified at time of analysis. No EPSS score was provided, so exploitation probability cannot be quantified. The technical impact is genuinely high - an out-of-bounds write inside the UEFI-MM Secure Partition corrupts the most privileged firmware trust domain on the platform, below the OS - but practical priority is tempered by the likely requirement of pre-existing kernel-level code execution. Net: a serious firmware-integrity issue worth patching on affected AmpereOne fleets, but the headline 9.8 overstates real-world ease of exploitation given the SMC-based local trigger. |
| Exploit ScenarioDerived | An attacker who has already achieved kernel-level (EL1) code execution on an affected AmpereOne server issues a deliberately malformed SMC call to the UEFI-MM MMCommunicate service, passing a crafted buffer/length the handler fails to validate. The resulting out-of-bounds write corrupts memory inside the UEFI-MM Secure Partition, allowing escalation from OS kernel into the higher-privileged Secure Partition firmware context and potential persistence below the operating system. No public exploit code is identified at time of analysis. |
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Alert meAnalysisAIv1 – Oct 05, 2026
An out-of-bounds write in the UEFI-MM Secure Partition of Ampere AmpereOne platform firmware can be triggered by a malformed SMC (Secure Monitor Call) issued to the MMCommunicate service, allowing memory corruption inside the secure partition context on affected devices running firmware earlier than AC03 3.5.9.3, AC04 4.4.5.2, or AmpereOne M 5.4.5.1. Although the NVD-published CVSS 3.1 vector scores this 9.8 with AV:N/PR:N, that rating does not match the attack surface: the MMCommunicate SMC interface is a local, privileged interface, and our independent assessment reassesses the flaw as CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H, meaning an attacker must already hold OS kernel/EL1-level execution on the host before reaching the vulnerable code. There is no indication of active exploitation (not in CISA KEV) and no public exploit code identified at time of analysis, so real-world risk is gated behind a prior operating-system compromise rather than direct remote reachability. Full technical details and fixed firmware versions are published by the vendor in advisory AMP-SB-0007.
RemediationAI
Vendor-released patches addressing this issue are available as firmware updates: upgrade AmpereOne AC03 devices to 3.5.9.3 or later, AmpereOne AC04 devices to 4.4.5.2 or later, and AmpereOne M devices to 5.4.5.1 or later, following the instructions in Ampere security bulletin AMP-SB-0007 (https://amperecomputing.com/products/security-bulletins/amp-sb-0007) and the product security page (https://amperecomputing.com/products/product-security). Because exploitation requires the ability to issue an SMC to the UEFI-MM MMCommunicate service - which in practice means an attacker has already obtained privileged kernel/EL1 code execution on the host - the most effective compensating controls are those that prevent that prerequisite and reduce blast radius: enforce Secure Boot and firmware image signature verification (blocks tampering with the BMC/flash image, with the trade-off that unsigned or custom firmware can no longer be loaded), restrict and monitor kernel-module loading, /dev/mem and any raw MMIO/SMC-brokering interfaces via kernel lockdown mode and module signature enforcement (trade-off: may break out-of-tree drivers), and keep privileged access tightly audited and least-privilege. Note that blocking network ports or remote access does not mitigate this class of flaw, since the vulnerable interface is not remotely reachable; the only definitive fix is applying the fixed firmware for the relevant product family. No public exploit code was identified at time of analysis, so prioritizing patching on a normal firmware-update cadence is reasonable, though the memory-corruption nature of the bug and the S:C scope change warrant prompt scheduling for internet-exposed or multi-tenant AmpereOne hosts.
Affects your stack
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Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
AmpereOne server SoCs implement Arm's Firmware Framework for Arm A-profile (FF-A) architecture, in which a UEFI Memory Management (UEFI-MM) component runs as an isolated Secure Partition at a lower exception level than the normal world. Normal-world software, including the OS kernel at EL1, communicates with that partition through the MMCommunicate protocol, invoked via an SMC (Secure Monitor Call) that traps into EL3 and is then routed into the S-EL0/S-EL1 secure partition. CVE-2025-62864 is a CWE-787 out-of-bounds write: when the MMCommunicate handler receives an incorrectly formed request, it fails to adequately validate the caller-supplied buffer/length fields before writing, so data is written past the bounds of the intended buffer inside the UEFI-MM Secure Partition. Because the corruption occurs in a partition with higher privilege than the caller and the security scope is changed (S:C in the assessed vector), a successful exploit can undermine the isolation boundary that UEFI-MM is meant to enforce, affecting confidentiality, integrity, and availability of the secure-partition context. The CPE data identifies this as a firmware-level issue spanning AmpereOne AC03, AC04, and AmpereOne M product lines and their specific SKU firmware images (A192-32M, A192-26M, A160-28M, A144-33M, A144-26M, A96-36M, A96-36X, A128-34X, A144-24X, A144-27X, and related A160-28X, A192-26X, A192-32X variants).
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SMC calls to UEFI-MM require local kernel-level privilege (AV:L, PR:H); the OOB write crosses from the OS into the more-privileged Secure Partition trust domain (S:C) with full C/I/A impact.
Primary rating from Vendor (mitre).
CVSS VectorVendor: mitre
DescriptionCVE.org
Ampere AmpereOne AC03 devices before 3.5.9.3, AmpereOne AC04 devices before 4.4.5.2, and AmpereOne M devices before 5.4.5.1 allow an incorrectly formed SMC call to UEFI-MM MMCommunicate service that could result in an out-of-bounds write within the UEFI-MM Secure Partition context.
Executive ViewAI
Ampere AmpereOne platform firmware contains a critical memory-corruption flaw in its UEFI-MM Secure Partition that could allow an attacker with existing OS kernel/EL1-level access to disrupt or compromise a trusted firmware component on affected systems. No vendor-released patch identified at time of analysis and no public exploit identified at time of analysis, so the immediate business risk is concentrated in environments where adversaries have already achieved privileged host access. Leadership should prioritize inventory of affected AmpereOne deployments and vendor engagement, because a successful exploit could enable post-compromise persistence or integrity loss in firmware-level security functions.
No vendor-released patch identified at time of analysis; interim mitigations include restricting kernel/EL1 access, enforcing least privilege, enabling Secure Boot and module signing, monitoring SMC/MMCommunicate activity, limiting console and physical access, isolating affected systems, and engaging Ampere for firmware mitigation guidance.
Threat Intelligence Overview
NVD
CVE.org
EPSS
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.
Affected Products (CPE)CVE.org
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