CVE-2026-63388 (GCVE-0-2026-63388)

Vulnerability from cvelistv5 – Published: 2026-08-20 17:44 – Updated: 2026-08-20 17:44
VLAI
Title
Libevent: Heap out-of-bounds write in bufferevent_socket_set_conn_address_ reachable via AF_UNIX accept
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 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.
Severity
8.4 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
Assigner
References
Impacted products
Vendor Product Version CPE status
libevent libevent Affected: < 2.1.13
Affected: >= 2.2.0-alpha, < 2.2.2-alpha
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "libevent",
          "vendor": "libevent",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.1.13"
            },
            {
              "status": "affected",
              "version": "\u003e= 2.2.0-alpha, \u003c 2.2.2-alpha"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 8.4,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-617",
              "description": "CWE-617: Reachable Assertion",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-787",
              "description": "CWE-787: Out-of-bounds Write",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-20T17:44:18.435Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/libevent/libevent/security/advisories/GHSA-cvq5-vrvr-j338",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/libevent/libevent/security/advisories/GHSA-cvq5-vrvr-j338"
        },
        {
          "name": "https://github.com/libevent/libevent/commit/52057cb33d0c20c0a0453fbabe6c0c96854931b9",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libevent/libevent/commit/52057cb33d0c20c0a0453fbabe6c0c96854931b9"
        },
        {
          "name": "https://github.com/libevent/libevent/commit/ef38f926e9cd1f082416c6fff13587bc1f431d72",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libevent/libevent/commit/ef38f926e9cd1f082416c6fff13587bc1f431d72"
        },
        {
          "name": "https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable"
        },
        {
          "name": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha"
        }
      ],
      "source": {
        "advisory": "GHSA-cvq5-vrvr-j338",
        "discovery": "UNKNOWN"
      },
      "title": "Libevent: Heap out-of-bounds write in bufferevent_socket_set_conn_address_ reachable via AF_UNIX accept"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-63388",
    "datePublished": "2026-08-20T17:44:18.435Z",
    "dateReserved": "2026-07-16T17:39:30.171Z",
    "dateUpdated": "2026-08-20T17:44:18.435Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-63388\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-20T18:16:36.893\",\"lastModified\":\"2026-08-20T18:16:36.893\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"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\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"libevent\",\"product\":\"libevent\",\"versions\":[{\"version\":\"\u003c 2.1.13\",\"status\":\"affected\"},{\"version\":\"\u003e= 2.2.0-alpha, \u003c 2.2.2-alpha\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":8.4,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.5,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-617\"},{\"lang\":\"en\",\"value\":\"CWE-787\"}]}],\"references\":[{\"url\":\"https://github.com/libevent/libevent/commit/52057cb33d0c20c0a0453fbabe6c0c96854931b9\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libevent/libevent/commit/ef38f926e9cd1f082416c6fff13587bc1f431d72\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libevent/libevent/security/advisories/GHSA-cvq5-vrvr-j338\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}



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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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