---
id: CVE-2026-63388
title: Libevent is an event notification library
summary: >-
  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 buffer…
severity: high
cvss: 8.4
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-617
  - CWE-787
vendor: libevent
product: libevent
affected:
  - libevent < 2.1.13
  - 'libevent >= 2.2.0-alpha, < 2.2.2-alpha'
published: '2026-08-20'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:19:49.197'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63388'
references:
  - url: >-
      https://github.com/libevent/libevent/commit/52057cb33d0c20c0a0453fbabe6c0c96854931b9
    label: security-advisories@github.com
  - url: >-
      https://github.com/libevent/libevent/commit/ef38f926e9cd1f082416c6fff13587bc1f431d72
    label: security-advisories@github.com
  - url: 'https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable'
    label: security-advisories@github.com
  - url: 'https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha'
    label: security-advisories@github.com
  - url: >-
      https://github.com/libevent/libevent/security/advisories/GHSA-cvq5-vrvr-j338
    label: security-advisories@github.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63388.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-63388'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2520661'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-63388'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63388'
  - url: 'https://access.redhat.com/errata/RHSA-2026:60853'
  - url: 'https://access.redhat.com/errata/RHSA-2026:67909'
  - url: 'https://access.redhat.com/errata/RHSA-2026:67908'
  - url: 'https://access.redhat.com/errata/RHSA-2026:67910'
  - url: 'https://access.redhat.com/errata/RHSA-2026:71603'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-08-21T21:00:24.903079Z'
ingestedAt: '2026-09-13T16:08:38.505Z'
epss: 0.00196
epssPercentile: 0.0824
patched:
  - hardened_images
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **RHSA-2026:60853** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-29 · [advisory](https://access.redhat.com/errata/RHSA-2026:60853)
- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat OpenShift Container Platform 4 · updated 2026-09-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63388.json)
- **RHSA-2026:67909** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10) · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:67909)
- **RHSA-2026:67908** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux BaseOS (v. 8) · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:67908)
- **RHSA-2026:67910** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9) · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:67910)
- **RHSA-2026:71603** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-09-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:71603)