CVE-2025-20083: Intel Slim Bootloader Privilege Escalation

CVE-2025-20083 Overview

CVE-2025-20083 is an improper authentication vulnerability [CWE-287] in the firmware for the Intel Slim Bootloader. A privileged local user can exploit the flaw to escalate privileges on affected systems. The weakness lives in the boot chain, so successful exploitation undermines trust boundaries established before the operating system loads.

Intel published details in Security Advisory SA-01290. The vulnerability requires local access and existing high privileges, but a successful attack yields high impact on confidentiality, integrity, and availability of the platform.

Critical Impact
Successful exploitation allows a privileged attacker to escalate privileges through firmware-level authentication weaknesses, compromising the platform trust chain established during boot.

Affected Products

Intel Slim Bootloader firmware (see Intel Security Advisory SA-01290 for exact affected versions)
Systems and reference designs that integrate the Intel Slim Bootloader
Downstream OEM firmware images built on vulnerable Slim Bootloader releases

Discovery Timeline

2025-05-13 - CVE-2025-20083 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-20083

Vulnerability Analysis

The defect is an improper authentication issue [CWE-287] inside the Slim Bootloader firmware. Slim Bootloader is Intel's open-source boot firmware used as an alternative to full UEFI implementations on select Intel platforms. Because the bootloader runs before the operating system, any authentication weakness in this component impacts the platform's root of trust.

An attacker with existing privileged local access can bypass or subvert authentication checks the bootloader performs. This exposes firmware operations, configuration data, or update paths that should require stronger verification. The result is escalation to a privilege level higher than the attacker initially held, potentially reaching firmware-resident execution.

The attack requires local access, high privileges, and no user interaction. The high attack complexity indicates non-trivial preconditions or timing must be satisfied for reliable exploitation.

Root Cause

The root cause is missing or insufficient authentication logic in a firmware code path that should validate the requester before performing a sensitive operation. Because Slim Bootloader executes with platform-level privileges, an authentication gap at this layer allows an already privileged process to reach state and interfaces reserved for lower-level firmware operations.

Attack Vector

Exploitation requires local access to the target and high privileges within the operating system, such as an administrator or root account. The attacker interacts with firmware interfaces exposed to privileged software and triggers the unauthenticated code path. There is no remote or network component to the attack. No user interaction is required beyond the attacker's own actions.

No public proof-of-concept code, exploit database entry, or CISA Known Exploited Vulnerabilities Catalog listing is associated with CVE-2025-20083 as of the last NVD update. Intel has not published exploit specifics beyond the advisory description.

Detection Methods for CVE-2025-20083

Indicators of Compromise

Unexpected changes to firmware version strings, Slim Bootloader configuration blocks, or boot policy after routine reboots
Privileged processes issuing SMM, MSR, or firmware-update related calls outside of documented vendor tools
Unsigned or unexpected firmware capsule updates appearing in platform logs

Detection Strategies

Monitor firmware measurement values reported to the Trusted Platform Module (TPM) and alert on drift between known-good and observed PCR values
Correlate elevated-process activity with access to firmware update interfaces such as UEFI capsule APIs or vendor firmware update services
Baseline the expected Slim Bootloader version across the fleet and flag hosts running versions listed as vulnerable in Intel SA-01290

Monitoring Recommendations

Enable and forward platform firmware and Windows Event Log firmware measurement events to a central data lake for retention and analytics
Track administrative and root-level command execution that touches firmware tooling, flashrom, or vendor update utilities
Review endpoint telemetry for privilege escalation patterns preceding firmware modification attempts

How to Mitigate CVE-2025-20083

Immediate Actions Required

Inventory systems that use Intel Slim Bootloader firmware, including OEM and ODM devices that redistribute it
Apply the firmware update referenced in Intel Security Advisory SA-01290 as soon as vendor images are available
Restrict local administrative and root access on affected hosts to reduce the population of accounts capable of exploiting the flaw
Verify firmware measurements against a known-good baseline after patching

Patch Information

Intel has issued updated Slim Bootloader firmware addressing the improper authentication condition. Consult Intel Security Advisory SA-01290 for the specific fixed versions and coordinate with the OEM supplying the platform firmware, since Slim Bootloader is typically shipped as part of an integrated firmware image.

Workarounds

Enforce least privilege so that day-to-day accounts cannot reach the high-privilege local context required for exploitation
Enable measured boot and remote attestation to detect firmware tampering even when patching is delayed
Disable or restrict firmware update mechanisms exposed to the operating system until validated firmware is deployed

bash

# Example: verify Slim Bootloader version and TPM PCR values on Linux
sudo dmidecode -t bios | grep -Ei 'vendor|version|release'
sudo tpm2_pcrread sha256:0,2,4,7