CVE-2025-21666

In the Linux kernel, the following vulnerability has been resolved:

vsock: prevent null-ptr-deref in vsock_*[has_data|has_space]

Recent reports have shown how we sometimes call vsock_*_has_data() when a vsock socket has been de-assigned from a transport (see attached links), but we shouldn't.

Previous commits should have solved the real problems, but we may have more in the future, so to avoid null-ptr-deref, we can return 0 (no space, no data available) but with a warning.

This way the code should continue to run in a nearly consistent state and have a warning that allows us to debug future problems.

This vulnerability is rated as having a Moderate impact because exploitation is constrained to a local denial of service via a kernel null-pointer dereference, with no risk of code execution or privilege escalation. In typical Red Hat Enterprise Linux deployments, AF_VSOCK sockets are utilized primarily for guest-to-host hypervisor communications. An unprivileged local attacker must establish and manipulate virtual socket state transitions to trigger the fault and crash the operating system.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.