CVE-2026-63388: Libevent

High severity, CVSS 8.4. EPSS: 0.1% chance of exploitation in the next 30 days.

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a heap out-of-bounds write in bufferevent_sock.c when bufferevent_socket_set_conn_address_ copies a kernel-supplied AF_UNIX peer address into bufferevent_private.conn_address. Release builds compiled with NDEBUG disable the EVUTIL_ASSERT length guard, and the evhttp accept path can pass a 110-byte sockaddr from accept() into the 28-byte field. An unauthenticated local peer able to connect to an AF_UNIX listener can overwrite the adjacent dns_request pointer and heap data, causing memory corruption with confidentiality, integrity, and availability impact. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

Affected products

• Libevent Libevent: before 2.1.13 (fixed in 2.1.13); from 2.2.0-alpha, before 2.2.2-alpha (fixed in 2.2.2-alpha)

Published 2026-08-20. Last modified 2026-09-09.