What’s Vulnerable › Vulnerabilities

CVE-2026-63388: Libevent: Heap out-of-bounds write in bufferevent_socket_set_conn_address_ reachable via AF_UNIX accept

• Severity: high (CVSS 8.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-20 · updated 2026-10-26
• Weakness: CWE-617

Description

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: before 2.1.13; from 2.2.0-alpha, < 2.2.2-alpha

References

• https://github.com/libevent/libevent/commit/52057cb33d0c20c0a0453fbabe6c0c96854931b9
• https://github.com/libevent/libevent/commit/ef38f926e9cd1f082416c6fff13587bc1f431d72
• https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable
• https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha
• https://github.com/libevent/libevent/security/advisories/GHSA-cvq5-vrvr-j338

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