In the Linux kernel, the following vulnerability has been resolved: net/handshake: hand off the pinned file reference to accept_doit handshake_req_next() removes the request from the per-net pending list and drops hn_lock before handshake_nl_accept_doit() reads req->hr_sk->sk_socket and dereferences sock->file (once in FD_PREPARE() and again in get_file()). In that window a consumer running tls_handshake_cancel() followed by sockfd_put() (svc_sock_free) or __fput_sync() (xs_reset_transport) releases sock->file. sock_release() then runs sock_orphan(), zeroing sk_socket, and frees the struct socket. The accept-side code either reads NULL through sk_socket or chases freed memory. The submit-side sock_hold() does not prevent this. sk_refcnt protects struct sock, but struct socket and sock->file are independently refcounted via the file descriptor the consumer owns. Pinning sk leaves sock and sock->file unprotected. Retarget the accept-side dereferences at req->hr_file, which was pinned at submit time, instead of req->hr_sk->sk_socket->file. Pinning on its own is not sufficient: a consumer that cancels between handshake_req_next() returning and accept_doit reaching FD_PREPARE() takes the !remove_pending() branch in handshake_req_cancel() and drops hr_file before the accept side takes its own reference. Hand off an additional file reference inside handshake_req_next(), under hn_lock, so the accept side operates on a reference that no concurrent handshake_req_cancel() can revoke. FD_PREPARE() consumes that handed-off reference, either by transferring it to the new fd in fd_publish() or by dropping it in the cleanup destructor on error; the explicit get_file() that previously balanced FD_PREPARE() is therefore redundant and goes away. Update handshake_req_cancel_test2 and _test3 to simulate the FD_PREPARE() consumption with an fput() so the kunit file-count assertions stay balanced.

An update of the linux package has been released.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - net/handshake: hand off the pinned file reference to accept_doit handshake_req_next() removes the request     from the per-net pending list and drops hn_lock before handshake_nl_accept_doit() reads     req->hr_sk->sk_socket and dereferences sock->file (once in FD_PREPARE() and again in get_file()). In that     window a consumer running tls_handshake_cancel() followed by sockfd_put() (svc_sock_free) or __fput_sync()     (xs_reset_transport) releases sock->file. sock_release() then runs sock_orphan(), zeroing sk_socket, and     frees the struct socket. The accept-side code either reads NULL through sk_socket or chases freed memory.
    The submit-side sock_hold() does not prevent this. sk_refcnt protects struct sock, but struct socket and     sock->file are independently refcounted via the file descriptor the consumer owns. Pinning sk leaves sock     and sock->file unprotected. Retarget the accept-side dereferences at req->hr_file, which was pinned at     submit time, instead of req->hr_sk->sk_socket->file. Pinning on its own is not sufficient: a consumer that     cancels between handshake_req_next() returning and accept_doit reaching FD_PREPARE() takes the     !remove_pending() branch in handshake_req_cancel() and drops hr_file before the accept side takes its own     reference. Hand off an additional file reference inside handshake_req_next(), under hn_lock, so the accept     side operates on a reference that no concurrent handshake_req_cancel() can revoke. FD_PREPARE() consumes     that handed-off reference, either by transferring it to the new fd in fd_publish() or by dropping it in     the cleanup destructor on error; the explicit get_file() that previously balanced FD_PREPARE() is     therefore redundant and goes away. Update handshake_req_cancel_test2 and _test3 to simulate the     FD_PREPARE() consumption with an fput() so the kunit file-count assertions stay balanced. (CVE-2026-63979)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
340681	Ubuntu 24.04 LTS / 26.04 LTS / Pro Realtime 24.04 LTS : Linux kernel (NVIDIA) vulnerabilities (USN-8663-1)	Nessus	Ubuntu Local Security Checks	Local	high
340045	Ubuntu 26.04 LTS : Linux kernel (NVIDIA BaseOS) vulnerabilities (USN-8664-1)	Nessus	Ubuntu Local Security Checks	Local	high
339767	Photon OS 5.0: Linux PHSA-2026-5.0-92-0973	Nessus	PhotonOS Local Security Checks	Local	critical
339766	Photon OS 5.0: Linux PHSA-2026-5.0-91-0973	Nessus	PhotonOS Local Security Checks	Local	critical
327939	Linux Distros Unpatched Vulnerability : CVE-2026-63979	Nessus	Misc.	Local	critical

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