CVE-2026-68218: Linux Kernel Use-After-Free Vulnerability

CVE-2026-68218 Overview

CVE-2026-68218 is a memory leak vulnerability in the Linux kernel's dm1105 media PCI driver. The driver failed to destroy an allocated workqueue in its remove() callback, leaving kernel resources unreleased when the driver is unloaded. Maintainers resolved the issue by adding a workqueue destruction call to the remove path, ensuring proper cleanup of allocated resources.

The fix has been backported across multiple stable Linux kernel branches through the commits referenced in the advisory. The flaw is classified as a kernel-space [CWE-401] memory leak affecting the DVB (Digital Video Broadcasting) card driver subsystem.

Critical Impact
Repeated load and unload of the dm1105 driver leaks kernel memory, degrading system stability over time and potentially contributing to resource exhaustion conditions on long-running hosts.

Affected Products

Linux kernel drivers/media/pci/dm1105 component
Linux stable kernel branches receiving the referenced backports
Systems using DM1105-based PCI DVB tuner cards

Discovery Timeline

2026-08-10 - CVE-2026-68218 published to NVD
2026-08-10 - Last updated in NVD database

Technical Details for CVE-2026-68218

Vulnerability Analysis

The dm1105 driver manages PCI-based DVB tuner hardware in the Linux media subsystem. During probe, the driver allocates a workqueue to handle deferred hardware processing. The original remove() callback did not call the corresponding workqueue destruction routine, so the workqueue and its backing kernel objects remained allocated after driver teardown.

Each unload cycle leaks the workqueue and its associated worker thread structures. On systems that repeatedly bind, unbind, or hot-plug the driver, this leak accumulates and consumes kernel memory that cannot be reclaimed without a reboot.

The issue is a resource management defect rather than a memory-safety bug that grants execution or disclosure primitives. However, kernel-space leaks reduce availability and can contribute to denial-of-service conditions on hosts with constrained memory or long uptime requirements.

Root Cause

The root cause is a missing cleanup call in the driver's remove() path. The probe path allocates a workqueue but the symmetric release call was omitted, breaking the allocation and free pairing that the kernel workqueue API requires.

Attack Vector

Exploitation requires local access to load and unload the dm1105 driver, which is a privileged operation. A privileged user or automated udev workflow that repeatedly rebinds DM1105 hardware can incrementally exhaust kernel memory. Remote exploitation is not applicable to this defect.

No public proof of concept is associated with CVE-2026-68218 and no exploitation activity has been reported. See the Kernel Git Commit 08ddfd6 and Kernel Git Commit 1a65db2 references for the corrective patches.

Detection Methods for CVE-2026-68218

Indicators of Compromise

Growth in kernel slab allocations attributable to workqueue objects on hosts with DM1105 hardware.
Repeated dm1105 driver bind and unbind events in dmesg or journalctl -k without a corresponding reboot.
Gradual decrease in available kernel memory reported by /proc/meminfo on affected systems.

Detection Strategies

Inventory Linux hosts running kernel versions predating the referenced stable fixes and identify those loading the dm1105 module via lsmod.
Monitor kernel memory statistics with tools such as slabtop or kmemleak on systems where DM1105 hardware is present.
Correlate driver rebind events with kernel memory growth in centralized log analytics.

Monitoring Recommendations

Ingest kernel logs and process telemetry from Linux endpoints into a centralized data lake for longitudinal analysis of memory-usage trends.
Alert on abnormal kernel memory growth on hosts that host media capture or DVB workloads.
Track patch state for Linux kernel packages across the fleet to confirm remediation coverage.

How to Mitigate CVE-2026-68218

Immediate Actions Required

Apply the latest Linux stable kernel update that includes the dm1105 workqueue destruction fix for your distribution branch.
Reboot affected hosts after patching to release previously leaked workqueue allocations.
If patching is delayed, avoid repeated unload and reload of the dm1105 module in production.

Patch Information

The fix destroys the allocated workqueue in the driver's remove() callback. The corrective changes are tracked in five upstream commits: Kernel Git Commit 08ddfd6, Kernel Git Commit 0c2b4c4, Kernel Git Commit 1a65db2, Kernel Git Commit 46715fe, and Kernel Git Commit 8d753c8. Distribution vendors backport these commits to supported stable branches.

Workarounds

Blacklist the dm1105 module on hosts that do not require DVB tuner functionality using /etc/modprobe.d/.
Schedule routine reboots on affected systems until the patched kernel is deployed.
Restrict administrative access that permits arbitrary module bind and unbind operations.

bash

# Blacklist the dm1105 driver until the patched kernel is deployed
echo "blacklist dm1105" | sudo tee /etc/modprobe.d/blacklist-dm1105.conf
sudo update-initramfs -u
# Verify the module is not loaded after reboot
lsmod | grep dm1105