CVE-2026-53181

/// Technical description

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

vsock/vmci: fix sk_ack_backlog leak on failed handshake

When vmci_transport_recv_connecting_server() returns an error,

vmci_transport_recv_listen() calls vsock_remove_pending() but never

calls sk_acceptq_removed(). This leaves sk_ack_backlog incremented

permanently.

Repeated handshake failures (malformed packets, queue pair alloc

failure, event subscribe failure) cause sk_ack_backlog to climb

toward sk_max_ack_backlog. Once it reaches the limit the listener

permanently refuses all new connections with -ECONNREFUSED, a

silent denial of service requiring a process restart to recover.

The two existing sk_acceptq_removed() calls in af_vsock.c do not

cover this path: line 764 checks vsock_is_pending() which returns

false after vsock_remove_pending(), and line 1889 is only reached

on successful accept().

Fix by balancing sk_acceptq_added() with sk_acceptq_removed() on

the error path.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References