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PatchSiren cyber security CVE debrief

CVE-2026-46021 Linux CVE debrief

This CVE addresses two related vulnerabilities in the Linux kernel thermal management subsystem. The first issue involves a memory leak that occurs when thermal_zone_device_register_with_trips() fails after adding a thermal governor to a thermal zone—the governor is not properly removed during error cleanup. The second issue is a race condition in thermal_zone_device_unregister(), which calls thermal_set_governor() without holding the thermal zone lock, potentially racing with governor updates via sysfs and leading to use-after-free conditions. The fix adds proper thermal_set_governor() calls in both thermal_release() for cleanup and in the registration error path to handle failures before device registration completes.

Vendor
Linux
Product
Unknown
CVSS
Unknown
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-27
Original CVE updated
2026-05-27
Advisory published
2026-05-27
Advisory updated
2026-05-27

Who should care

Linux system administrators managing thermal-sensitive workloads, kernel maintainers, and security teams monitoring kernel-level memory safety issues

Technical summary

The vulnerability exists in the Linux kernel thermal core subsystem. The first flaw is a memory leak occurring when thermal_zone_device_register_with_trips() fails after governor attachment but before registration completion, leaving the governor reference uncleared. The second flaw is a locking deficiency where thermal_zone_device_unregister() invokes thermal_set_governor() without acquiring the thermal zone mutex, creating a race window with concurrent sysfs governor updates that could result in use-after-free memory corruption. The resolution adds defensive thermal_set_governor() invocations in thermal_release() for proper governor detachment and in the registration error path for pre-registration failure cleanup.

Defensive priority

medium

Recommended defensive actions

  • Apply kernel updates containing the referenced stable commits when available from your Linux distribution
  • Monitor vendor security advisories for kernel package updates addressing this thermal subsystem fix
  • Review systems utilizing thermal zone management for unusual memory consumption patterns
  • Ensure thermal governor configurations via sysfs are performed during maintenance windows to minimize race condition exposure

Evidence notes

The vulnerability description is sourced from the official CVE record and NVD entry. The fix involves kernel-level changes to thermal zone governor management with commits referenced in the source material. No CVSS score has been assigned as of the CVE publication date.

Official resources

2026-05-27