UBUNTU-CVE-2026-63381 (CVE-2026-63381)

Vulnerability from osv_ubuntu – Published: 2026-08-21 00:00 – Updated: 2026-09-02 16:20 – Source website
VLAI
Details

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a use-after-free in buffer.c when evbuffer_add_buffer_reference processes an output buffer whose out_total_len is zero. evbuffer_free_all_chains frees the initial empty chain without resetting outbuf->first, outbuf->last, or outbuf->last_with_datap, and APPEND_CHAIN_MULTICAST subsequently dereferences the dangling chain pointer. A caller that can drive this buffer state can cause memory corruption or a process crash. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

Severity
5.8 (Medium)
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libevent-2.1-6",
            "binary_version": "2.1.8-stable-4ubuntu0.1~esm1"
          },
          {
            "binary_name": "libevent-core-2.1-6",
            "binary_version": "2.1.8-stable-4ubuntu0.1~esm1"
          },
          {
            "binary_name": "libevent-extra-2.1-6",
            "binary_version": "2.1.8-stable-4ubuntu0.1~esm1"
          },
          {
            "binary_name": "libevent-openssl-2.1-6",
            "binary_version": "2.1.8-stable-4ubuntu0.1~esm1"
          },
          {
            "binary_name": "libevent-pthreads-2.1-6",
            "binary_version": "2.1.8-stable-4ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "libevent",
        "purl": "pkg:deb/ubuntu/libevent@2.1.8-stable-4ubuntu0.1~esm1?arch=source\u0026distro=esm-infra/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.8-stable-4ubuntu0.1~esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.1.8-stable-4",
        "2.1.8-stable-4build1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libevent-2.1-7",
            "binary_version": "2.1.11-stable-1ubuntu0.1~esm1"
          },
          {
            "binary_name": "libevent-core-2.1-7",
            "binary_version": "2.1.11-stable-1ubuntu0.1~esm1"
          },
          {
            "binary_name": "libevent-extra-2.1-7",
            "binary_version": "2.1.11-stable-1ubuntu0.1~esm1"
          },
          {
            "binary_name": "libevent-openssl-2.1-7",
            "binary_version": "2.1.11-stable-1ubuntu0.1~esm1"
          },
          {
            "binary_name": "libevent-pthreads-2.1-7",
            "binary_version": "2.1.11-stable-1ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "libevent",
        "purl": "pkg:deb/ubuntu/libevent@2.1.11-stable-1ubuntu0.1~esm1?arch=source\u0026distro=esm-infra/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.11-stable-1ubuntu0.1~esm1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.1.8-stable-4build1",
        "2.1.11-stable-1~exp0",
        "2.1.11-stable-1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libevent-2.1-7",
            "binary_version": "2.1.12-stable-1ubuntu0.1"
          },
          {
            "binary_name": "libevent-core-2.1-7",
            "binary_version": "2.1.12-stable-1ubuntu0.1"
          },
          {
            "binary_name": "libevent-extra-2.1-7",
            "binary_version": "2.1.12-stable-1ubuntu0.1"
          },
          {
            "binary_name": "libevent-openssl-2.1-7",
            "binary_version": "2.1.12-stable-1ubuntu0.1"
          },
          {
            "binary_name": "libevent-pthreads-2.1-7",
            "binary_version": "2.1.12-stable-1ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "libevent",
        "purl": "pkg:deb/ubuntu/libevent@2.1.12-stable-1ubuntu0.1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.12-stable-1ubuntu0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.1.12-stable-1",
        "2.1.12-stable-1build1",
        "2.1.12-stable-1build2",
        "2.1.12-stable-1build3"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libevent-2.1-7t64",
            "binary_version": "2.1.12-stable-9ubuntu2.1"
          },
          {
            "binary_name": "libevent-core-2.1-7t64",
            "binary_version": "2.1.12-stable-9ubuntu2.1"
          },
          {
            "binary_name": "libevent-extra-2.1-7t64",
            "binary_version": "2.1.12-stable-9ubuntu2.1"
          },
          {
            "binary_name": "libevent-openssl-2.1-7t64",
            "binary_version": "2.1.12-stable-9ubuntu2.1"
          },
          {
            "binary_name": "libevent-pthreads-2.1-7t64",
            "binary_version": "2.1.12-stable-9ubuntu2.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "libevent",
        "purl": "pkg:deb/ubuntu/libevent@2.1.12-stable-9ubuntu2.1?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.12-stable-9ubuntu2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.1.12-stable-9",
        "2.1.12-stable-9ubuntu2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libevent-2.1-7t64",
            "binary_version": "2.1.12-stable-10ubuntu0.1"
          },
          {
            "binary_name": "libevent-core-2.1-7t64",
            "binary_version": "2.1.12-stable-10ubuntu0.1"
          },
          {
            "binary_name": "libevent-extra-2.1-7t64",
            "binary_version": "2.1.12-stable-10ubuntu0.1"
          },
          {
            "binary_name": "libevent-openssl-2.1-7t64",
            "binary_version": "2.1.12-stable-10ubuntu0.1"
          },
          {
            "binary_name": "libevent-pthreads-2.1-7t64",
            "binary_version": "2.1.12-stable-10ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "libevent",
        "purl": "pkg:deb/ubuntu/libevent@2.1.12-stable-10ubuntu0.1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.12-stable-10ubuntu0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.1.12-stable-10build1",
        "2.1.12-stable-10build2"
      ]
    }
  ],
  "aliases": [],
  "details": "Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a use-after-free in buffer.c when evbuffer_add_buffer_reference processes an output buffer whose out_total_len is zero. evbuffer_free_all_chains frees the initial empty chain without resetting outbuf-\u003efirst, outbuf-\u003elast, or outbuf-\u003elast_with_datap, and APPEND_CHAIN_MULTICAST subsequently dereferences the dangling chain pointer. A caller that can drive this buffer state can cause memory corruption or a process crash. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.",
  "id": "UBUNTU-CVE-2026-63381",
  "modified": "2026-09-02T16:20:06Z",
  "published": "2026-08-21T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-63381"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-63381"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8710-1"
    }
  ],
  "related": [
    "USN-8710-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-63381"
  ]
}



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