CVE-2026-23045: Linux Kernel Race Condition Vulnerability

CVE-2026-23045 Overview

A race condition vulnerability has been identified in the Linux kernel's Amazon Elastic Network Adapter (ENA) driver. The vulnerability exists due to a missing lock when updating devlink parameters, specifically when calling devl_param_driverinit_value_set() in the ena_devlink_alloc() function. This improper synchronization can lead to system instability and potential denial of service conditions on affected systems.

Critical Impact

Systems running affected Linux kernel versions with the ENA network driver may experience kernel warnings, system instability, or denial of service due to race conditions in devlink parameter updates.

Affected Products

• Linux kernel with ENA (Elastic Network Adapter) driver
• Amazon EC2 instances using ENA networking
• Systems running Linux kernel version 6.19.0-rc2 and potentially earlier versions

Discovery Timeline

• 2026-02-04 - CVE CVE-2026-23045 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2026-23045

Vulnerability Analysis

This vulnerability is a race condition that occurs within the Linux kernel's ENA (Elastic Network Adapter) driver during device initialization. The issue stems from improper locking discipline when the driver attempts to set devlink driver-initialization parameter values. The kernel's devlink subsystem requires proper lock acquisition before modifying parameters, but the ENA driver was calling devl_param_driverinit_value_set() without first acquiring the necessary devlink instance lock.

When the ENA driver probes a new network device during ena_probe(), it allocates devlink resources via ena_devlink_alloc(). During this allocation process, the driver attempts to set driver-initialized parameter values, which triggers a lock assertion failure in the devlink core code at net/devlink/core.c:261. This manifests as a kernel WARNING with a full call trace, indicating the improper synchronization.

Root Cause

The root cause is a missing call to acquire the devlink instance lock (devl_lock()) before invoking devl_param_driverinit_value_set() in the ena_devlink_alloc() function. The devlink subsystem enforces strict locking requirements through assertion checks, and the ENA driver failed to comply with these requirements when setting driver-initialized parameter values during device probing.

Attack Vector

This is a local vulnerability that can be triggered during normal system operation when the ENA network driver initializes or when network devices are hotplugged. While the immediate impact is a kernel warning and potential system instability, repeated triggering of this race condition could lead to denial of service. The vulnerability occurs in the context of a kernel worker thread (kworker/0:0) processing device probe operations.

The vulnerability is triggered through the following call path:

• ena_probe() → ena_devlink_alloc() → devl_param_driverinit_value_set() → devl_assert_locked() (fails)

Detection Methods for CVE-2026-23045

Indicators of Compromise

• Kernel warning messages containing devl_assert_locked in system logs
• Stack traces showing ena_devlink_alloc and devl_param_driverinit_value_set in the call chain
• System log entries referencing net/devlink/core.c:261
• Repeated kernel warnings during ENA network device initialization

Detection Strategies

• Monitor kernel logs (dmesg, /var/log/kern.log, or journalctl) for WARNING messages related to devl_assert_locked
• Implement alerting on kernel call traces containing ENA driver modules ([ena])
• Use kernel tracing tools (ftrace, eBPF) to monitor devlink lock acquisition patterns
• Deploy SentinelOne Singularity platform to detect anomalous kernel behavior and system instability patterns

Monitoring Recommendations

• Configure centralized logging to capture kernel warnings from all affected systems
• Set up alerts for repeated kernel warnings that may indicate exploitation attempts or system instability
• Monitor system stability metrics on Amazon EC2 instances using ENA networking
• Implement kernel live patching monitoring to verify patch deployment status

How to Mitigate CVE-2026-23045

Immediate Actions Required

• Apply the kernel patches referenced in the kernel git commits
• Update to a patched Linux kernel version that includes the fix
• Monitor affected systems for kernel warnings and system instability
• Plan maintenance windows for kernel updates on production systems

Patch Information

The Linux kernel maintainers have released patches to address this vulnerability. The fix adds proper devlink instance lock acquisition before calling devl_param_driverinit_value_set() in the ENA driver. The patches are available through the following kernel git commits:

• Kernel Git Commit 8da901ff
• Kernel Git Commit f2c4bcfa

Organizations should update to kernel versions containing these commits or apply the patches to their custom kernel builds.

Workarounds

• If immediate patching is not possible, consider temporarily disabling devlink functionality for ENA devices where feasible
• Implement rate limiting on kernel warning messages to prevent log flooding
• Monitor systems closely for signs of instability until patches can be applied
• Consider using alternative network drivers if available and compatible with your infrastructure

# Check current kernel version
uname -r

# Verify ENA driver is loaded
lsmod | grep ena

# Monitor for kernel warnings related to this issue
dmesg | grep -i "devl_assert_locked\|ena_devlink"

# Check kernel logs for related warnings
journalctl -k | grep -E "(devl_assert_locked|ena.*devlink)"