CVE-2025-21086: Intel 700 Series Ethernet Privilege Escalation

CVE-2025-21086 Overview

CVE-2025-21086 is an improper input validation vulnerability in the Linux kernel-mode driver for certain Intel 700 Series Ethernet controllers. The flaw affects driver versions before 2.28.5. An authenticated local user can leverage the weakness to escalate privileges on the host system.

The vulnerability is classified under [CWE-20] Improper Input Validation. Exploitation requires local access and low privileges, but no user interaction. Intel published details in security advisory SA-01335.

Critical Impact
Successful exploitation allows an authenticated local user to escalate privileges through the kernel-mode Ethernet driver, potentially achieving kernel-level code execution on affected Linux hosts.

Affected Products

Intel 700 Series Ethernet Controllers running the Linux kernel-mode driver
Intel Linux Ethernet driver versions prior to 2.28.5
Linux hosts configured with vulnerable Intel 700 Series network hardware

Discovery Timeline

2025-08-12 - CVE-2025-21086 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-21086

Vulnerability Analysis

The vulnerability resides in the Linux kernel-mode driver supplied by Intel for its 700 Series Ethernet controllers. The driver fails to properly validate input received through its interfaces before acting on it in kernel context. An authenticated local user can craft malformed input that reaches the vulnerable code path.

Because the driver executes in kernel mode, invalid input handled without sanitization can corrupt kernel state or divert execution flow. This provides a path from a low-privilege user account to elevated privileges. The impact focuses on integrity and availability of the affected system rather than confidentiality.

Root Cause

The root cause is missing or insufficient input validation ([CWE-20]) inside driver routines exposed to userspace. Data supplied by a local caller is trusted without adequate bounds or type checking. This gap allows unexpected values to be processed by kernel logic that assumes well-formed input.

Attack Vector

The attack vector is local. An adversary must already have authenticated access to a Linux host running the affected Intel driver. From that foothold, the attacker interacts with driver interfaces exposed to userland to trigger the unsafe code path. No user interaction from another party is required.

See the Intel Security Advisory SA-01335 for vendor technical details. No public proof-of-concept exploit is currently available, and the flaw is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2025-21086

Indicators of Compromise

Unexpected kernel oops, panic, or stack traces referencing the Intel i40e or related 700 Series Ethernet driver modules
New root-owned processes or SUID binaries created shortly after driver interaction by a non-privileged user
Modifications to /etc/passwd, /etc/shadow, or SSH authorized keys following local session activity

Detection Strategies

Inventory Linux hosts to identify those loading Intel 700 Series Ethernet drivers with versions below 2.28.5 using modinfo and ethtool -i
Monitor dmesg and journalctl -k output for driver-related warnings, faults, or unusual ioctl activity from non-root users
Correlate local logon events with subsequent privileged process creation to spot local escalation patterns

Monitoring Recommendations

Enable Linux audit rules for ioctl, setsockopt, and netlink interactions against network driver interfaces
Alert on loading of unexpected kernel modules or reloads of the Intel Ethernet driver on production systems
Forward kernel telemetry into a centralized analytics platform for correlation across the fleet and behavioral baselining

How to Mitigate CVE-2025-21086

Immediate Actions Required

Upgrade the Intel 700 Series Linux kernel-mode Ethernet driver to version 2.28.5 or later on all affected hosts
Restrict local shell access to trusted administrators and enforce least-privilege for interactive accounts
Audit systems that host the vulnerable driver for signs of prior privilege escalation attempts

Patch Information

Intel addresses this vulnerability in Linux driver version 2.28.5 and later. Refer to Intel Security Advisory SA-01335 for the official patched packages and installation instructions. Apply the update through vendor-supplied packages or the distribution channel providing the updated driver.

Workarounds

Where the driver is not required, unload it with modprobe -r and blacklist the module until patching is possible
Limit local user accounts on hosts that cannot be immediately updated to reduce the pool of potential attackers
Apply Linux Security Module policies (SELinux, AppArmor) to constrain non-privileged user interaction with network device interfaces

bash

# Verify installed Intel Ethernet driver version and upgrade path
ethtool -i eth0 | grep -E "driver|version"
modinfo i40e | grep -E "^version|^filename"

# After installing the patched package (>= 2.28.5), reload the module
sudo modprobe -r i40e
sudo modprobe i40e
dmesg | tail -n 20