CVE-2026-53181: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.1% chance of exploitation in the next 30 days.

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.

Affected products

• Linux Linux Kernel: from 3.9, before 5.10.259 (fixed in 5.10.259); from 5.11, before 5.15.210 (fixed in 5.15.210); from 5.16, before 6.1.176 (fixed in 6.1.176); from 6.2, before 6.6.143 (fixed in 6.6.143); from 6.7, before 6.12.94 (fixed in 6.12.94); from 6.13, before 6.18.36 (fixed in 6.18.36); …

Published 2026-06-25. Last modified 2026-07-06.