CVE-2025-62627: VMWare ESXi Information Disclosure Flaw

CVE-2025-62627 Overview

CVE-2025-62627 is an untrusted pointer dereference vulnerability [CWE-822] in the ionic cloud driver for VMware ESXi. An attacker operating an unprivileged virtual machine can trigger the flaw to read kernel memory or memory belonging to co-located guest VMs. The result is a loss of confidentiality and potential loss of availability on the host. AMD published a security bulletin tracking the issue.

Critical Impact

An unprivileged guest VM can read hypervisor kernel memory or co-located guest memory, breaking tenant isolation on shared ESXi hosts.

Affected Products

• VMware ESXi hosts running the ionic cloud driver
• AMD Pensando ionic-based network adapters operating under ESXi
• Multi-tenant virtualization environments using the affected driver stack

Discovery Timeline

• 2026-05-13 - CVE-2025-62627 published to NVD
• 2026-05-13 - Last updated in NVD database

Technical Details for CVE-2025-62627

Vulnerability Analysis

The vulnerability resides in the ionic cloud driver, a kernel-mode component on VMware ESXi that services AMD Pensando network hardware. The driver dereferences a pointer that originates from, or is influenced by, an untrusted source without validating that the pointer references memory the caller is permitted to access.

Because the driver executes in the hypervisor kernel context, dereferencing an attacker-controlled pointer exposes memory regions that should remain isolated from guest workloads. This breaks the confidentiality boundary that separates an unprivileged VM from the hypervisor and from other tenants on the same host. Exploitation requires local access via a guest VM and elevated attack complexity, but the attacker only needs low privileges within their own VM.

Root Cause

The root cause is improper validation of a pointer value before dereference, classified as [CWE-822: Untrusted Pointer Dereference]. The driver trusts a pointer that can be shaped or influenced through the guest interface and reads memory at that location, returning kernel or cross-guest data to the caller.

Attack Vector

An attacker with low privileges inside an unprivileged guest VM issues crafted requests to the ionic driver interface exposed through the virtualization stack. By controlling the pointer value consumed by the driver, the attacker induces reads of arbitrary kernel addresses or addresses mapped to neighboring guests. The condition can also corrupt driver state, leading to denial of service on the ESXi host.

No public proof-of-concept code is available. Technical details are documented in the AMD Security Bulletin AMD-SB-2001.

Detection Methods for CVE-2025-62627

Indicators of Compromise

• Unexpected ESXi host kernel warnings or PSOD events referencing the ionic driver module
• Repeated driver-level errors in vmkernel.log correlated with activity from a specific guest VM
• Anomalous device control or ioctl-style traffic from guest VMs targeting the ionic interface

Detection Strategies

• Monitor ESXi host logs for ionic driver fault traces, null or invalid address reads, and kernel exceptions
• Baseline expected driver interaction patterns per VM and alert on outliers in volume or sequence
• Correlate guest-side process activity with host-side driver errors to attribute suspicious calls to a specific tenant

Monitoring Recommendations

• Forward ESXi vmkernel.log and hostd.log to a centralized logging platform for retention and analysis
• Track AMD and VMware advisory feeds for updated driver versions and indicators
• Enable hypervisor integrity monitoring on multi-tenant clusters to flag unexpected memory access patterns

How to Mitigate CVE-2025-62627

Immediate Actions Required

• Inventory all ESXi hosts running the ionic cloud driver and identify hosts shared across tenants
• Apply the driver update referenced in the AMD Security Bulletin AMD-SB-2001 once available from VMware or the hardware vendor
• Restrict workload placement so that untrusted or low-trust VMs do not co-reside with sensitive workloads on affected hosts

Patch Information

Refer to the AMD Security Bulletin AMD-SB-2001 for the authoritative list of affected driver versions and fixed releases. Coordinate driver updates with VMware ESXi patch cycles and validate the driver version on each host after upgrade.

Workarounds

• Disable or unload the ionic cloud driver on hosts that do not require AMD Pensando network functionality
• Migrate sensitive workloads to ESXi hosts that do not expose the affected driver to guests
• Apply strict tenant segregation policies and avoid co-locating untrusted VMs with privileged workloads until patched

# Identify ionic driver presence and version on an ESXi host
esxcli software vib list | grep -i ionic
vmkload_mod -l | grep -i ionic