Unrated

UBUNTU-CVE-2026-63495

Type: withdrawalSource: OSV1 source record

Libevent is an event notification library. From 2.2.0-alpha-dev until 2.2.2-alpha, the libevent WebSocket server in ws.c accumulates fragmented frames in evws->incomplete_frames without enforcing a total message-size limit. An unauthenticated remote client can repeatedly send fragmented WebSocket frames below WS_MAX_RECV_FRAME_SZ with FIN=0, causing the evbuffer to grow without bound until the process or host exhausts memory. This issue is fixed in version 2.2.2-alpha.

Announced 20 Aug 2026Source revision 1

Original source ↗

UBUNTU-CVE-2026-63495

Primary source · Revision 1 · Withdrawn

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

Security context

Source reference: osv:UBUNTU-CVE-2026-63495

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: Not stated in this record
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: Not stated in this record
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: Not stated in this record
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: Not stated in this record
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: Not stated in this record
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: Not stated in this record
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: Not stated in this record
Prerequisites: Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
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          {
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          }
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    "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/cve/2026/UBUNTU-CVE-2026-63495.json"
    },
    "ecosystem_specific": {
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      "purl": "pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra-legacy%2Fxenial",
      "ecosystem": "Ubuntu:Pro:16.04:LTS"
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    "versions": [
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    },
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        },
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        },
        {
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          "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm1"
        },
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          "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm1"
        },
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  },
  {
    "ranges": [
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    ],
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      "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/cve/2026/UBUNTU-CVE-2026-63495.json"
    },
    "ecosystem_specific": {
      "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"
        }
      ]
    }
  },
  {
    "ranges": [
      {
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        "events": [
          {
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          }
        ]
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    ],
    "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/cve/2026/UBUNTU-CVE-2026-63495.json"
    },
    "ecosystem_specific": {
      "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"
        }
      ]
    }
  },
  {
    "ranges": [
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    ],
    "package": {
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      "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/cve/2026/UBUNTU-CVE-2026-63495.json"
    },
    "ecosystem_specific": {
      "binaries": [
        {
          "binary_name": "libevent-2.1-7",
          "binary_version": "2.1.12-stable-1ubuntu0.1"
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        {
          "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"
        }
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  },
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      "name": "libevent",
      "purl": "pkg:deb/ubuntu/libevent?arch=source&distro=noble",
      "ecosystem": "Ubuntu:24.04:LTS"
    },
    "versions": [
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      "2.1.12-stable-9ubuntu2",
      "2.1.12-stable-9ubuntu2.1"
    ],
    "database_specific": {
      "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63495.json"
    },
    "ecosystem_specific": {
      "binaries": [
        {
          "binary_name": "libevent-2.1-7t64",
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        },
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          "binary_name": "libevent-core-2.1-7t64",
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        },
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          "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"
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      "purl": "pkg:deb/ubuntu/libevent?arch=source&distro=resolute",
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      "2.1.12-stable-10ubuntu0.1"
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    },
    "ecosystem_specific": {
      "binaries": [
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        },
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          "binary_version": "2.1.12-stable-10ubuntu0.1"
        },
        {
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          "binary_version": "2.1.12-stable-10ubuntu0.1"
        },
        {
          "binary_name": "libevent-openssl-2.1-7t64",
          "binary_version": "2.1.12-stable-10ubuntu0.1"
        },
        {
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          "binary_version": "2.1.12-stable-10ubuntu0.1"
        }
      ]
    }
  }
]

Publisher severity

No explicit severity was provided.

Event: #6067 · Revision 1
Added to Heist Feed: Sat, 24 Oct 2026 22:21:34 GMT
Publisher date: Thu, 20 Aug 2026 18:16:00 GMT

Read the original announcement