CVE-2025-40018: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-40018 was disclosed on October 24, 2025, affecting the Linux kernel's IPVS (IP Virtual Server) module. The vulnerability involves a use-after-free issue in the IP Virtual Server FTP connection tracking functionality during network namespace cleanup operations (NVD).

The vulnerability occurs when ipvsftpexit() may unregister ipvsftp before connections with valid cp->app pointers are flushed during the netns cleanup path. The fix introduces a global 'exitingmodule' flag that is set to true in ipvsftp_exit() before unregistering the pernet subsystem. The ipvsftpexit() function is modified to skip ipvsftp unregister during netns cleanup when exitingmodule is false, deferring it to _ipvscleanupbatch() which unregisters all apps after connections are flushed (NVD). Red Hat has assigned this vulnerability a CVSSv3 base score of 7.0, indicating high severity (Red Hat Security).

The vulnerability could lead to a use-after-free condition in the Linux kernel's IPVS module, potentially causing system instability or crashes. This affects various Linux distributions including Red Hat Enterprise Linux, Debian, and other Linux kernel-based systems (Debian Security).

The vulnerability has been patched in the Linux kernel. System administrators should apply the latest kernel updates available for their distributions. Multiple Linux distributions have released or are in the process of releasing security updates to address this vulnerability (Debian Security).