CVE-2026-53286: Linux Kernel Use-After-Free Vulnerability

CVE-2026-53286 Overview

CVE-2026-53286 is a Linux kernel vulnerability in the Intel Infrastructure Data Path Function (idpf) network driver. The flaw involves a double free and use-after-free condition in the auxiliary device error paths. When auxiliary_device_add() fails inside idpf_plug_vport_aux_dev() or idpf_plug_core_aux_dev(), the error handling logic frees the same memory twice and reads from memory that has already been released.

The issue is a regression of a previously fixed use-after-free tracked in commit 65637c3a1811, which addressed the unplug path but missed both probe error paths. The kernel maintainers have since resolved the issue in the mainline tree.

Critical Impact
Successful triggering of the error path can corrupt kernel memory, leading to kernel panics, denial of service, or potential local privilege escalation on systems using the idpf driver.

Affected Products

Linux kernel builds containing the idpf driver prior to the fix commits
Systems using Intel Infrastructure Data Path Function (IDPF) network adapters
Distributions shipping the affected kernel versions before backporting the patch

Discovery Timeline

2026-06-26 - CVE-2026-53286 published to NVD
2026-06-30 - Last updated in NVD database

Technical Details for CVE-2026-53286

Vulnerability Analysis

The vulnerability resides in the idpf driver's auxiliary device plug routines. Both idpf_plug_vport_aux_dev() and idpf_plug_core_aux_dev() register an auxiliary device via auxiliary_device_add(). When that call fails, control transfers to the err_aux_dev_add label, which invokes auxiliary_device_uninit() and then falls through into the err_aux_dev_init cleanup block.

The auxiliary_device_uninit() call triggers put_device(), which drops the final reference and executes the release callback (idpf_vport_adev_release or idpf_core_adev_release). That release callback calls kfree() on the iadev structure, freeing the memory. The fall-through code then dereferences adev->id on the already-freed iadev to call ida_free(), and subsequently calls kfree(iadev) again, producing both a use-after-free [CWE-416] read and a double free [CWE-415].

Root Cause

The root cause is incorrect ordering of cleanup operations in the error path. The IDA slot release and back-pointer clearing must happen while iadev is still valid, before the auxiliary_device_uninit() call that triggers memory deallocation via the release callback. The original patch for commit 65637c3a1811 corrected this pattern for the unplug path but did not propagate the fix to the two probe error paths in the same file.

Attack Vector

Triggering the flaw requires the kernel to reach the auxiliary_device_add() failure branch during idpf initialization. An attacker with the ability to influence auxiliary device registration, or a system encountering resource pressure during driver load, can hit the vulnerable code path. Exploitation of kernel double-free conditions can yield memory corruption suitable for privilege escalation, though the primary observable outcome is kernel instability.

No verified proof-of-concept has been published. See the fix commits Kernel Git Commit 6c77b95, Kernel Git Commit 722b91d, and Kernel Git Commit f319de7 for the corrected cleanup ordering.

Detection Methods for CVE-2026-53286

Indicators of Compromise

Kernel oops or panic messages referencing idpf_plug_vport_aux_dev, idpf_plug_core_aux_dev, idpf_vport_adev_release, or idpf_core_adev_release in dmesg or /var/log/kern.log.
KASAN reports flagging use-after-free reads or double-free events in the idpf module on kernels built with CONFIG_KASAN=y.
Repeated auxiliary bus registration failures logged during driver probe on hosts with IDPF-capable network adapters.

Detection Strategies

Enumerate running kernel versions across the fleet and compare against the patched commits 6c77b951, 722b91d5, and f319de70 to identify unpatched hosts.
Enable KASAN and kmemleak on test systems to surface the double-free during driver stress testing.
Monitor kernel ring buffer output for idpf driver probe failures accompanied by slab corruption warnings.

Monitoring Recommendations

Forward dmesg and auditd events to a central log platform and alert on kernel warnings that reference idpf symbols.
Track unexpected reboots or kernel panics on hosts running Intel IDPF network adapters and correlate with driver load events.
Baseline auxiliary bus device registration counts and alert on repeated failures that could indicate the error path being triggered.

How to Mitigate CVE-2026-53286

Immediate Actions Required

Inventory all Linux hosts running the idpf driver, particularly systems with Intel IDPF-capable network hardware.
Apply distribution kernel updates that incorporate the upstream fix commits as soon as they are available.
Restrict local access to affected systems until patched, as the vulnerability requires interaction with driver initialization paths.

Patch Information

The fix reorders cleanup so that the IDA slot is released and the back-pointer cleared before auxiliary_device_uninit() is invoked, then returns immediately without falling through. The corrected code is available in kernel commits 6c77b9510829a424d1b74409b7db9456e3522871, 722b91d5086a249318c9d0e2b36aeac80ba8c808, and f319de7074e1728a9f9ff7134257360c694ec2b2. Rebuild or update the kernel to a release containing these commits and reboot affected systems.

Workarounds

Unload the idpf kernel module (modprobe -r idpf) on hosts that do not require IDPF network functionality until a patched kernel is deployed.
Blacklist the idpf module by adding blacklist idpf to /etc/modprobe.d/ on systems where the driver is not in use.
Limit local user access and restrict privileged operations on affected hosts to reduce the exposure window before patching.

bash

# Configuration example: blacklist the idpf module until the kernel is patched
echo "blacklist idpf" | sudo tee /etc/modprobe.d/blacklist-idpf.conf
sudo update-initramfs -u
# Verify the module is not loaded after reboot
lsmod | grep idpf