CVE-2026-63388
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.
CSIRTS triage
- What
- Libevent contains a heap out-of-bounds write in bufferevent_socket_set_conn_address_ triggered via AF_UNIX accept operations.
- Who is affected
- Applications using Libevent with AF_UNIX sockets and local attack vectors.
- Urgency
- High severity (CVSS 8.4) and not exploited; prioritize patching to prevent local privilege escalation.
- Action
- Update Libevent to a version that correctly bounds-checks connection address buffers in AF_UNIX socket handling.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.14% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 4% of all EPSS-scored CVEs.
Advisory coverage (2)
External references
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