CVE-2025-39865: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-39865 is a vulnerability discovered in the Linux kernel affecting the TEE (Trusted Execution Environment) subsystem, specifically related to a NULL pointer dereference in the teeshmput function. The vulnerability was disclosed on September 19, 2025, and affects various versions of the Linux kernel (NVD).

The vulnerability occurs in the teeshmput function where a NULL pointer dereference can happen during the shared memory cleanup process. The issue arises in the following sequence: _opteedisableshmcache calls regpairtoptr which may return NULL, followed by teeshmfree which calls teeshm_put, potentially leading to a system crash. The vulnerability has been assigned a CVSS v3.1 base score of 7.0 with attack vector Local (L), attack complexity High (H), and privileges required Low (PR) (Red Hat).

When exploited, this vulnerability can cause a kernel panic, resulting in system crashes. This is evidenced by the panic log showing an inability to handle kernel paging requests at virtual address 0000000000100cca, leading to a level 0 translation fault (NVD).

The vulnerability has been patched by adding a check in teeshmput to prevent the NULL pointer dereference. The fix has been implemented in various Linux distributions including Red Hat Enterprise Linux 8, 9, and 10 (Red Hat).