UnratedFix available

libevent vulnerabilities

Type: advisorySource: OSV1 source record

Michał Majchrowicz and Marcin Wyczechowski discovered that libevent incorrectly handled certain DNS responses. A remote attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-63387) It was discovered that libevent incorrectly handled certain connections. A local attacker could possibly use this issue to cause a denial of service or execute arbitrary code. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-63388)

Announced 28 Sept 2026Source revision 1

Original source ↗

USN-8840-1

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:USN-8840-1

libevent

Source reference: /affected/0/package/name

Affected versions: 2.0.21-stable-1
Source reference: /affected/0/versions
2.0.21-stable-1ubuntu1
Source reference: /affected/0/versions
2.0.21-stable-1ubuntu1.14.04.1
Source reference: /affected/0/versions
2.0.21-stable-1ubuntu1.14.04.2
Source reference: /affected/0/versions
2.0.21-stable-1ubuntu1.14.04.2+esm1
Source reference: /affected/0/versions
Fixed versions: 2.0.21-stable-1ubuntu1.14.04.2+esm2
Source reference: /affected/0/ranges
Prerequisites: Not stated in this record

libevent

Source reference: /affected/1/package/name

Affected versions: 2.0.21-stable-2
Source reference: /affected/1/versions
2.0.21-stable-2ubuntu0.16.04.1
Source reference: /affected/1/versions
2.0.21-stable-2ubuntu0.16.04.1+esm1
Source reference: /affected/1/versions
Fixed versions: 2.0.21-stable-2ubuntu0.16.04.1+esm2
Source reference: /affected/1/ranges
Prerequisites: Not stated in this record

libevent

Source reference: /affected/2/package/name

Affected versions: 2.1.8-stable-4
Source reference: /affected/2/versions
2.1.8-stable-4build1
Source reference: /affected/2/versions
2.1.8-stable-4ubuntu0.1~esm1
Source reference: /affected/2/versions
Fixed versions: 2.1.8-stable-4ubuntu0.1~esm2
Source reference: /affected/2/ranges
Prerequisites: Not stated in this record

libevent

Source reference: /affected/3/package/name

Affected versions: 2.1.8-stable-4build1
Source reference: /affected/3/versions
2.1.11-stable-1~exp0
Source reference: /affected/3/versions
2.1.11-stable-1
Source reference: /affected/3/versions
2.1.11-stable-1ubuntu0.1~esm1
Source reference: /affected/3/versions
Fixed versions: 2.1.11-stable-1ubuntu0.1~esm2
Source reference: /affected/3/ranges
Prerequisites: Not stated in this record

libevent

Source reference: /affected/4/package/name

Affected versions: 2.1.12-stable-1
Source reference: /affected/4/versions
2.1.12-stable-1build1
Source reference: /affected/4/versions
2.1.12-stable-1build2
Source reference: /affected/4/versions
2.1.12-stable-1build3
Source reference: /affected/4/versions
2.1.12-stable-1ubuntu0.1
Source reference: /affected/4/versions
Fixed versions: 2.1.12-stable-1ubuntu0.2
Source reference: /affected/4/ranges
Prerequisites: Not stated in this record

libevent

Source reference: /affected/5/package/name

Affected versions: 2.1.12-stable-9
Source reference: /affected/5/versions
2.1.12-stable-9ubuntu2
Source reference: /affected/5/versions
2.1.12-stable-9ubuntu2.1
Source reference: /affected/5/versions
Fixed versions: 2.1.12-stable-9ubuntu2.2
Source reference: /affected/5/ranges
Prerequisites: Not stated in this record

libevent

Source reference: /affected/6/package/name

Affected versions: 2.1.12-stable-10build1
Source reference: /affected/6/versions
2.1.12-stable-10build2
Source reference: /affected/6/versions
2.1.12-stable-10ubuntu0.1
Source reference: /affected/6/versions
Fixed versions: 2.1.12-stable-10ubuntu0.2
Source reference: /affected/6/ranges
Prerequisites: Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "2.0.21-stable-1ubuntu1.14.04.2+esm2"
          }
        ]
      }
    ],
    "package": {
      "name": "libevent",
      "purl": "pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra-legacy%2Ftrusty",
      "ecosystem": "Ubuntu:Pro:14.04:LTS"
    },
    "versions": [
      "2.0.21-stable-1",
      "2.0.21-stable-1ubuntu1",
      "2.0.21-stable-1ubuntu1.14.04.1",
      "2.0.21-stable-1ubuntu1.14.04.2",
      "2.0.21-stable-1ubuntu1.14.04.2+esm1"
    ],
    "database_specific": {
      "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json",
      "cves_map": {
        "cves": [],
        "ecosystem": "Ubuntu:Pro:14.04:LTS"
      }
    },
    "ecosystem_specific": {
      "binaries": [
        {
          "binary_name": "libevent-2.0-5",
          "binary_version": "2.0.21-stable-1ubuntu1.14.04.2+esm2"
        },
        {
          "binary_name": "libevent-core-2.0-5",
          "binary_version": "2.0.21-stable-1ubuntu1.14.04.2+esm2"
        },
        {
          "binary_name": "libevent-extra-2.0-5",
          "binary_version": "2.0.21-stable-1ubuntu1.14.04.2+esm2"
        },
        {
          "binary_name": "libevent-openssl-2.0-5",
          "binary_version": "2.0.21-stable-1ubuntu1.14.04.2+esm2"
        },
        {
          "binary_name": "libevent-pthreads-2.0-5",
          "binary_version": "2.0.21-stable-1ubuntu1.14.04.2+esm2"
        }
      ],
      "availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "2.0.21-stable-2ubuntu0.16.04.1+esm2"
          }
        ]
      }
    ],
    "package": {
      "name": "libevent",
      "purl": "pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra-legacy%2Fxenial",
      "ecosystem": "Ubuntu:Pro:16.04:LTS"
    },
    "versions": [
      "2.0.21-stable-2",
      "2.0.21-stable-2ubuntu0.16.04.1",
      "2.0.21-stable-2ubuntu0.16.04.1+esm1"
    ],
    "database_specific": {
      "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json",
      "cves_map": {
        "cves": [],
        "ecosystem": "Ubuntu:Pro:16.04:LTS"
      }
    },
    "ecosystem_specific": {
      "binaries": [
        {
          "binary_name": "libevent-2.0-5",
          "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm2"
        },
        {
          "binary_name": "libevent-core-2.0-5",
          "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm2"
        },
        {
          "binary_name": "libevent-extra-2.0-5",
          "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm2"
        },
        {
          "binary_name": "libevent-openssl-2.0-5",
          "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm2"
        },
        {
          "binary_name": "libevent-pthreads-2.0-5",
          "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm2"
        }
      ],
      "availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "2.1.8-stable-4ubuntu0.1~esm2"
          }
        ]
      }
    ],
    "package": {
      "name": "libevent",
      "purl": "pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra%2Fbionic",
      "ecosystem": "Ubuntu:Pro:18.04:LTS"
    },
    "versions": [
      "2.1.8-stable-4",
      "2.1.8-stable-4build1",
      "2.1.8-stable-4ubuntu0.1~esm1"
    ],
    "database_specific": {
      "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json",
      "cves_map": {
        "cves": [
          {
            "id": "CVE-2026-63388",
            "severity": [
              {
                "type": "CVSS_V3",
                "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
              },
              {
                "type": "Ubuntu",
                "score": "medium"
              }
            ]
          }
        ],
        "ecosystem": "Ubuntu:Pro:18.04:LTS"
      }
    },
    "ecosystem_specific": {
      "binaries": [
        {
          "binary_name": "libevent-2.1-6",
          "binary_version": "2.1.8-stable-4ubuntu0.1~esm2"
        },
        {
          "binary_name": "libevent-core-2.1-6",
          "binary_version": "2.1.8-stable-4ubuntu0.1~esm2"
        },
        {
          "binary_name": "libevent-extra-2.1-6",
          "binary_version": "2.1.8-stable-4ubuntu0.1~esm2"
        },
        {
          "binary_name": "libevent-openssl-2.1-6",
          "binary_version": "2.1.8-stable-4ubuntu0.1~esm2"
        },
        {
          "binary_name": "libevent-pthreads-2.1-6",
          "binary_version": "2.1.8-stable-4ubuntu0.1~esm2"
        }
      ],
      "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "2.1.11-stable-1ubuntu0.1~esm2"
          }
        ]
      }
    ],
    "package": {
      "name": "libevent",
      "purl": "pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra%2Ffocal",
      "ecosystem": "Ubuntu:Pro:20.04:LTS"
    },
    "versions": [
      "2.1.8-stable-4build1",
      "2.1.11-stable-1~exp0",
      "2.1.11-stable-1",
      "2.1.11-stable-1ubuntu0.1~esm1"
    ],
    "database_specific": {
      "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json",
      "cves_map": {
        "cves": [
          {
            "id": "CVE-2026-63388",
            "severity": [
              {
                "type": "CVSS_V3",
                "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
              },
              {
                "type": "Ubuntu",
                "score": "medium"
              }
            ]
          }
        ],
        "ecosystem": "Ubuntu:Pro:20.04:LTS"
      }
    },
    "ecosystem_specific": {
      "binaries": [
        {
          "binary_name": "libevent-2.1-7",
          "binary_version": "2.1.11-stable-1ubuntu0.1~esm2"
        },
        {
          "binary_name": "libevent-core-2.1-7",
          "binary_version": "2.1.11-stable-1ubuntu0.1~esm2"
        },
        {
          "binary_name": "libevent-extra-2.1-7",
          "binary_version": "2.1.11-stable-1ubuntu0.1~esm2"
        },
        {
          "binary_name": "libevent-openssl-2.1-7",
          "binary_version": "2.1.11-stable-1ubuntu0.1~esm2"
        },
        {
          "binary_name": "libevent-pthreads-2.1-7",
          "binary_version": "2.1.11-stable-1ubuntu0.1~esm2"
        }
      ],
      "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "2.1.12-stable-1ubuntu0.2"
          }
        ]
      }
    ],
    "package": {
      "name": "libevent",
      "purl": "pkg:deb/ubuntu/libevent?arch=source&distro=jammy",
      "ecosystem": "Ubuntu:22.04:LTS"
    },
    "versions": [
      "2.1.12-stable-1",
      "2.1.12-stable-1build1",
      "2.1.12-stable-1build2",
      "2.1.12-stable-1build3",
      "2.1.12-stable-1ubuntu0.1"
    ],
    "database_specific": {
      "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json",
      "cves_map": {
        "cves": [
          {
            "id": "CVE-2026-63388",
            "severity": [
              {
                "type": "CVSS_V3",
                "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
              },
              {
                "type": "Ubuntu",
                "score": "medium"
              }
            ]
          }
        ],
        "ecosystem": "Ubuntu:22.04:LTS"
      }
    },
    "ecosystem_specific": {
      "binaries": [
        {
          "binary_name": "libevent-2.1-7",
          "binary_version": "2.1.12-stable-1ubuntu0.2"
        },
        {
          "binary_name": "libevent-core-2.1-7",
          "binary_version": "2.1.12-stable-1ubuntu0.2"
        },
        {
          "binary_name": "libevent-extra-2.1-7",
          "binary_version": "2.1.12-stable-1ubuntu0.2"
        },
        {
          "binary_name": "libevent-openssl-2.1-7",
          "binary_version": "2.1.12-stable-1ubuntu0.2"
        },
        {
          "binary_name": "libevent-pthreads-2.1-7",
          "binary_version": "2.1.12-stable-1ubuntu0.2"
        }
      ],
      "availability": "No subscription required"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "2.1.12-stable-9ubuntu2.2"
          }
        ]
      }
    ],
    "package": {
      "name": "libevent",
      "purl": "pkg:deb/ubuntu/libevent?arch=source&distro=noble",
      "ecosystem": "Ubuntu:24.04:LTS"
    },
    "versions": [
      "2.1.12-stable-9",
      "2.1.12-stable-9ubuntu2",
      "2.1.12-stable-9ubuntu2.1"
    ],
    "database_specific": {
      "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json",
      "cves_map": {
        "cves": [
          {
            "id": "CVE-2026-63388",
            "severity": [
              {
                "type": "CVSS_V3",
                "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
              },
              {
                "type": "Ubuntu",
                "score": "medium"
              }
            ]
          }
        ],
        "ecosystem": "Ubuntu:24.04:LTS"
      }
    },
    "ecosystem_specific": {
      "binaries": [
        {
          "binary_name": "libevent-2.1-7t64",
          "binary_version": "2.1.12-stable-9ubuntu2.2"
        },
        {
          "binary_name": "libevent-core-2.1-7t64",
          "binary_version": "2.1.12-stable-9ubuntu2.2"
        },
        {
          "binary_name": "libevent-extra-2.1-7t64",
          "binary_version": "2.1.12-stable-9ubuntu2.2"
        },
        {
          "binary_name": "libevent-openssl-2.1-7t64",
          "binary_version": "2.1.12-stable-9ubuntu2.2"
        },
        {
          "binary_name": "libevent-pthreads-2.1-7t64",
          "binary_version": "2.1.12-stable-9ubuntu2.2"
        }
      ],
      "availability": "No subscription required"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "2.1.12-stable-10ubuntu0.2"
          }
        ]
      }
    ],
    "package": {
      "name": "libevent",
      "purl": "pkg:deb/ubuntu/libevent?arch=source&distro=resolute",
      "ecosystem": "Ubuntu:26.04:LTS"
    },
    "versions": [
      "2.1.12-stable-10build1",
      "2.1.12-stable-10build2",
      "2.1.12-stable-10ubuntu0.1"
    ],
    "database_specific": {
      "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json",
      "cves_map": {
        "cves": [
          {
            "id": "CVE-2026-63387",
            "severity": [
              {
                "type": "CVSS_V3",
                "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H"
              },
              {
                "type": "Ubuntu",
                "score": "medium"
              }
            ]
          },
          {
            "id": "CVE-2026-63388",
            "severity": [
              {
                "type": "CVSS_V3",
                "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
              },
              {
                "type": "Ubuntu",
                "score": "medium"
              }
            ]
          }
        ],
        "ecosystem": "Ubuntu:26.04:LTS"
      }
    },
    "ecosystem_specific": {
      "binaries": [
        {
          "binary_name": "libevent-2.1-7t64",
          "binary_version": "2.1.12-stable-10ubuntu0.2"
        },
        {
          "binary_name": "libevent-core-2.1-7t64",
          "binary_version": "2.1.12-stable-10ubuntu0.2"
        },
        {
          "binary_name": "libevent-extra-2.1-7t64",
          "binary_version": "2.1.12-stable-10ubuntu0.2"
        },
        {
          "binary_name": "libevent-openssl-2.1-7t64",
          "binary_version": "2.1.12-stable-10ubuntu0.2"
        },
        {
          "binary_name": "libevent-pthreads-2.1-7t64",
          "binary_version": "2.1.12-stable-10ubuntu0.2"
        }
      ],
      "availability": "No subscription required"
    }
  }
]

Publisher severity

No explicit severity was provided.

Event: #33259 · Revision 1
Added to Heist Feed: Sun, 25 Oct 2026 09:03:07 GMT
Publisher date: Mon, 28 Sep 2026 20:05:19 GMT

Read the original announcement