CVE-2022-50421: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-50421 is a vulnerability in the Linux kernel related to the rpmsg character device driver. The issue was disclosed on October 1, 2025, affecting the rpmsg subsystem's handling of default endpoints (NVD, Ubuntu).

The vulnerability stems from a double destroy issue in the default endpoint handling. Specifically, the rpmsg_dev_remove() function in rpmsg_core is responsible for releasing the default endpoint, but the same endpoint was also being destroyed in rpmsg_chrdev_eptdev_destroy(). This leads to a double destroy condition that causes the ept->refcount to report an underflow warning, indicating a potential use-after-free situation. The issue can be reproduced by stopping remoteproc before closing the /dev/rpmsgX device (RedHat).

The vulnerability has been assigned a CVSS v3.1 base score of 7.0 with the vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating potential high impacts on confidentiality, integrity, and availability when successfully exploited (RedHat).

The vulnerability has been resolved in the Linux kernel by modifying the endpoint destruction behavior to avoid the double destroy condition. The fix ensures that the default endpoint is only destroyed once, following the same pattern as rpmsg_eptdev_release() (NVD).