CVE-2026-53019: Linux Kernel DOS Vulnerability

CVE-2026-53019 Overview

CVE-2026-53019 is a Linux kernel vulnerability in the SpacemiT clock controller unit (CCU) driver. The flaw resides in the ccu_mix_trigger_fc() function within clk/spacemit/ccu_mix. An inverted conditional check causes the driver to skip the frequency change trigger during CPU frequency (cpufreq) scaling operations. The result is a kernel panic on affected SpacemiT-based platforms when cpufreq transitions occur. The issue has been resolved upstream through three stable-tree commits.

Critical Impact
Affected systems experience kernel panics during routine cpufreq scaling, leading to local denial of service on SpacemiT SoC platforms running vulnerable Linux kernel builds.

Affected Products

Linux kernel builds including the SpacemiT CCU mix clock driver (drivers/clk/spacemit/ccu_mix.c)
Stable kernel branches referenced in commits 16dfbc4e95c4, 54e97360b44b, and da99d0302d3c
SpacemiT SoC-based platforms relying on cpufreq scaling

Discovery Timeline

2026-06-24 - CVE-2026-53019 published to NVD
2026-06-24 - Last updated in NVD database

Technical Details for CVE-2026-53019

Vulnerability Analysis

The vulnerability is a logic error in the Linux kernel's SpacemiT clock controller driver. The ccu_mix_trigger_fc() helper is responsible for asserting the frequency change trigger bit when a mix clock is reprogrammed. Due to an inverted condition, the trigger path is bypassed under circumstances where it should execute. The CPU frequency governor relies on this trigger to complete the rate transition. When the trigger is skipped, the clock subsystem and CPU enter an inconsistent state, producing a kernel panic.

Root Cause

The root cause is a coding defect classified as a logic flaw in conditional evaluation. The boolean test guarding the frequency change trigger was written with reversed polarity. As a result, the code took the no-op branch on the path that required the trigger and attempted the trigger on the path that did not. The fix corrects the condition so the trigger executes only when the hardware requires it.

Attack Vector

The defect is reachable through normal kernel operation rather than crafted input. Any workload or governor action that drives a cpufreq transition on a SpacemiT platform can hit the faulty path. A local unprivileged user can plausibly induce frequency scaling under load and trigger the panic. Remote exploitation is not described in the upstream commit messages. The practical impact is local denial of service through kernel panic on vulnerable hardware.

No public proof-of-concept code is associated with this CVE. Technical details and the corrected condition are available in the upstream patches: kernel commit 16dfbc4e95c4, kernel commit 54e97360b44b, and kernel commit da99d0302d3c.

Detection Methods for CVE-2026-53019

Indicators of Compromise

Unexpected kernel panic messages referencing ccu_mix_trigger_fc or the SpacemiT CCU driver in dmesg and /var/log/kern.log.
Repeated system reboots or hangs correlated with cpufreq governor transitions on SpacemiT hardware.
Crash signatures in kdump captures pointing to drivers/clk/spacemit/ccu_mix.c.

Detection Strategies

Inventory Linux hosts running on SpacemiT SoCs and identify kernel versions that predate the fixing commits.
Compare installed kernel package versions against distribution advisories that cite CVE-2026-53019.
Review crash telemetry and reboot events for clustering around cpufreq scaling activity.

Monitoring Recommendations

Forward kernel logs and panic dumps to a centralized logging or SIEM platform for correlation.
Alert on kernel oops or panic events that reference clock driver symbols on embedded fleets.
Track cpufreq scaling failures and clock framework errors as leading indicators of the defect.

How to Mitigate CVE-2026-53019

Immediate Actions Required

Update affected systems to a Linux kernel build that includes commits 16dfbc4e95c4, 54e97360b44b, or da99d0302d3c.
For custom or vendor kernels, backport the corrected condition in ccu_mix_trigger_fc() from the upstream stable tree.
Reboot updated hosts to ensure the patched kernel image is active.

Patch Information

The fix is published in the Linux stable tree. Refer to the upstream patches at kernel commit 16dfbc4e95c4, kernel commit 54e97360b44b, and kernel commit da99d0302d3c. Vendors shipping SpacemiT platform kernels should release builds incorporating these changes.

Workarounds

Pin the cpufreq governor to performance to reduce frequency transitions that exercise the faulty path.
Disable cpufreq scaling on affected SpacemiT hosts where workload requirements allow.
Restrict local access to limit users who can drive load patterns that trigger frequent scaling events.

bash

# Temporarily pin cpufreq governor to performance to avoid scaling transitions
for cpu in /sys/devices/system/cpu/cpu[0-9]*/cpufreq/scaling_governor; do
    echo performance | sudo tee "$cpu"
done

# Verify governor is applied
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor