The Linux kernel vulnerability CVE-2026-64163 involves the kprobes testing framework where running the kprobes sanity tests twice causes all tests to fail and eventually crashes the kernel. This occurs because static kprobe variables retain leftover data after register and unregister operations, which is not fully cleared between test runs. Specifically, address and flags fields were not reset, causing subsequent register_kprobe calls to fail with error -22 and triggering kernel paging faults. The fix moves all kprobe cleanup operations into the kprobes_test_init function, which is called before each individual test, ensuring no residual data remains from previous runs.

Repeated execution of the kprobes sanity tests can cause kernel crashes due to improper cleanup of kprobe data structures. This can lead to system instability and denial of service during testing. The vulnerability affects the kernel testing framework rather than production kernel operation, limiting its impact primarily to kernel developers or testers running these specific tests.

A fix has been implemented that ensures all kprobe data is cleared before each test run by moving cleanup code into the kprobes_test_init function. Users should update to the patched Linux kernel version containing this fix. Since this is a kernel test framework issue, normal users are unlikely to be affected unless running these tests. Patch status is not explicitly stated; check the vendor or Linux kernel mailing lists for the official fixed version.