AmpereOne Firmware CVE-2025-62862

Exploitation requires the ability to issue SMC (Secure Monitor Call) instructions, which means the attacker must already hold privileged Non-Secure execution (EL1 / OS-kernel level) on an affected AmpereOne AC03, AC04, or M device running firmware below the fixed versions (3.5.9.3 / 4.4.5.2 / 5.4.5.1). The specific trigger is an incorrectly formed SMC call targeting the UEFI-MM Boot Error Record Table (BERT) driver. Limiting factors: this is local-only (no network vector), gated behind high privilege (PR:H - a non-privileged user-space process cannot issue the call), impact is bounded to memory mapped to the UEFI-MM Secure Partition by the Secure Partition Manager, and only unpatched firmware revisions are affected. No user interaction is required.

This is a genuinely low-to-moderate priority issue despite the memory-corruption primitive, and the signals are largely consistent in pointing that way. The CVSS 3.1 vector (AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:L, base 4.6) describes a locally exploitable flaw requiring high privileges - an attacker must already be able to issue SMC calls, i.e. hold EL1/kernel-level (privileged Non-Secure) execution. EPSS of 0.12% (2nd percentile) and the absence of any KEV listing or public exploit reinforce that mass or opportunistic exploitation is unlikely; this is a defense-in-depth / privilege-boundary hardening issue rather than an internet-facing emergency. One notable conflict: the vendor-supplied vector sets C:N, yet the description explicitly says the out-of-bounds read 'leaks Secure-EL0 information to a process running in Non-Secure state,' which is a real confidentiality impact across a trust boundary - the C:N rating appears to understate the information-disclosure path, verify with Ampere. No SSVC decision data was provided in the input. Overall: a confirmed cross-world (Secure/Non-Secure) boundary weakness that matters most in multi-tenant or confidential-computing contexts where the Non-Secure kernel is not fully trusted, but not a widespread-exploitation priority.

A local attacker who has already gained privileged (kernel-level) execution in the Non-Secure world - for example a compromised guest OS kernel or a malicious root process on an affected AmpereOne server - issues a deliberately malformed SMC call to the UEFI-MM Boot Error Record Table driver. The resulting out-of-bounds read leaks Secure-EL0 memory contents back to the Non-Secure process, or an out-of-bounds write corrupts memory within the UEFI-MM Secure Partition, undermining the Secure/Non-Secure isolation boundary. No public exploit identified at time of analysis; the high-privilege local prerequisite (PR:H) and low attack complexity mean exploitation is straightforward once that privilege level is held.