CVE-2025-24305: Intel Xeon Privilege Escalation Vulnerability

CVE-2025-24305 Overview

CVE-2025-24305 is a firmware vulnerability affecting the Alias Checking Trusted Module (ACTM) in some Intel Xeon processors. The flaw stems from insufficient control flow management [CWE-691] within the ACTM firmware. A privileged local user can leverage this weakness to potentially escalate privileges beyond the intended boundary. Intel published the issue in Security Advisory SA-01313, and Debian LTS distributed related updates through its October 2025 announcement. The vulnerability requires local access and high privileges, limiting the pool of viable attackers but raising the impact on multi-tenant and confidential-computing environments where the ACTM enforces trust boundaries.

Critical Impact
A privileged local user can escalate privileges on affected Intel Xeon systems by abusing weak control flow enforcement inside ACTM firmware, undermining trusted execution guarantees.

Affected Products

Intel Xeon processors with vulnerable Alias Checking Trusted Module (ACTM) firmware
Systems relying on Intel Trust Domain Extensions (TDX) that depend on ACTM integrity
Debian LTS systems shipping the affected Intel microcode package

Discovery Timeline

2025-08-12 - CVE-2025-24305 published to NVD
2025-10 - Debian LTS advisory issued for the affected microcode
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-24305

Vulnerability Analysis

The Alias Checking Trusted Module (ACTM) is Intel firmware that validates memory alias behavior for trusted execution features on Xeon processors. It participates in enforcing isolation between confidential workloads and the host platform. The ACTM firmware contains insufficient control flow management, mapped to [CWE-691]. When invoked under specific conditions, ACTM does not adequately constrain execution paths, allowing a privileged caller to reach code states that bypass intended integrity checks. The result is an escalation of privilege affecting the confidentiality and integrity of firmware-protected resources. Availability is not directly impacted based on the published metrics.

Root Cause

The root cause is missing or incomplete validation of control flow transitions inside ACTM firmware routines. Improper sequencing of state checks lets a caller drive the module into a state that was not intended to be reachable with attacker-controlled inputs. Because ACTM operates below the operating system boundary, weaknesses at this level erode the security guarantees relied upon by higher layers, including hypervisors and trusted domain managers.

Attack Vector

Exploitation requires local access with high privileges on the host, such as ring-0 kernel context or an equivalent platform-privileged agent. No user interaction is needed. Attack complexity is high, reflecting the specialized knowledge and timing required to reach the vulnerable ACTM entry paths. A successful attacker gains privileges beyond their existing role, which is especially significant on systems hosting confidential VMs or workloads that depend on ACTM to guarantee memory isolation. Public proof-of-concept code is not available at the time of publication, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

No verified exploit code is publicly available. See the Intel Security Advisory SA-01313 for firmware-level technical detail.

Detection Methods for CVE-2025-24305

Indicators of Compromise

No file-based or network IOCs have been published for this firmware-level flaw.
Unexpected microcode or BIOS/UEFI version regressions on affected Xeon hosts.
Kernel-mode components attempting undocumented interactions with ACTM interfaces.

Detection Strategies

Inventory Intel Xeon platforms and cross-reference microcode revisions against the fixed versions in Intel SA-01313.
Monitor privileged process activity, kernel driver loads, and firmware update operations on affected hosts.
Correlate host telemetry with hypervisor and TDX event logs to identify anomalous trust-domain state transitions.

Monitoring Recommendations

Alert on unauthorized microcode or BIOS changes and on loads of unsigned kernel drivers.
Track administrative logons and privileged command execution on Xeon-based hypervisors and bare-metal hosts.
Ingest platform firmware and hardware telemetry into a central data lake for long-term retention and threat hunting.

How to Mitigate CVE-2025-24305

Immediate Actions Required

Apply the Intel microcode and platform firmware updates referenced in Intel Security Advisory SA-01313.
On Debian systems, install the updated intel-microcode package per the Debian LTS Announcement.
Restrict root, hypervisor administrator, and platform management privileges to a minimum set of accounts.
Reboot affected hosts after updating microcode so the new firmware becomes active.

Patch Information

Intel released updated ACTM firmware and microcode as documented in Security Advisory SA-01313. Debian LTS shipped the corresponding intel-microcode update on 2025-10 via the referenced announcement. Administrators should validate the running microcode revision after boot and confirm it matches the version listed by Intel as remediated.

Workarounds

No software-only workaround eliminates the vulnerability; firmware update is required.
Reduce exposure by limiting local privileged access and enforcing strong administrative account controls.
Where feasible, disable or avoid workloads that depend on ACTM-protected trust boundaries until patched.

bash

# Verify and update Intel microcode on Debian-based systems
sudo apt update
sudo apt install --only-upgrade intel-microcode
# Confirm the running microcode revision after reboot
grep -m1 'microcode' /proc/cpuinfo