CVE-2025-40021: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-40021 was published on October 24, 2025, affecting the Linux kernel. The vulnerability relates to a missing lockdown check in the dynamicevents interface on tracefs, which should verify lockdown status similar to kprobeevents and uprobe_events interfaces (NVD).

The vulnerability involves the tracing subsystem's dynevent functionality in the Linux kernel. The issue stems from the dynamicevents interface on tracefs lacking proper lockdown status verification, despite being compatible with kprobeevents and uprobe_events interfaces. The vulnerability has been assigned a CVSS v3.1 base score of 5.5 with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating a low severity rating (Red Hat).

The vulnerability has been rated as low severity, primarily affecting system availability. The impact is limited to local attacks with no direct effects on confidentiality or integrity of the system (Red Hat).

For Debian systems, the fix has been implemented in version 6.16.12-2 and later releases. Red Hat has deferred fixes for affected versions of Red Hat Enterprise Linux 9 and 10. Systems running Red Hat Enterprise Linux 6, 7, and 8 are not affected and require no mitigation (Debian).