UBUNTU-CVE-2025-24356 (CVE-2025-24356)

Vulnerability from osv_ubuntu – Published: 2025-01-27 18:15 – Updated: 2025-10-24 05:18 – Source website
VLAI
Details

fastd is a VPN daemon which tunnels IP packets and Ethernet frames over UDP. When receiving a data packet from an unknown IP address/port combination, fastd will assume that one of its connected peers has moved to a new address and initiate a reconnect by sending a handshake packet. This "fast reconnect" avoids having to wait for a session timeout (up to ~90s) until a new connection is established. Even a 1-byte UDP packet just containing the fastd packet type header can trigger a much larger handshake packet (~150 bytes of UDP payload). Including IPv4 and UDP headers, the resulting amplification factor is roughly 12-13. By sending data packets with a spoofed source address to fastd instances reachable on the internet, this amplification of UDP traffic might be used to facilitate a Distributed Denial of Service attack. This vulnerability is fixed in v23.

Severity
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:L
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "fastd",
            "binary_version": "17-4ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "fastd",
        "purl": "pkg:deb/ubuntu/fastd@17-4ubuntu0.1?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "17-4",
        "17-4build1",
        "17-4ubuntu0.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "fastd",
            "binary_version": "18-3ubuntu0.18.04.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "fastd",
        "purl": "pkg:deb/ubuntu/fastd@18-3ubuntu0.18.04.1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "18-2",
        "18-2ubuntu1",
        "18-2ubuntu2",
        "18-3",
        "18-3ubuntu0.18.04.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "fastd",
            "binary_version": "18-3ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "fastd",
        "purl": "pkg:deb/ubuntu/fastd@18-3ubuntu0.1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "18-3build1",
        "18-3ubuntu0.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "fastd",
            "binary_version": "22-2build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "fastd",
        "purl": "pkg:deb/ubuntu/fastd@22-2build1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "21-1",
        "22-2",
        "22-2build1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "fastd",
            "binary_version": "22-4build2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "fastd",
        "purl": "pkg:deb/ubuntu/fastd@22-4build2?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "22-4",
        "22-4build1",
        "22-4build2"
      ]
    }
  ],
  "aliases": [],
  "details": "fastd is a VPN daemon which tunnels IP packets and Ethernet frames over UDP. When receiving a data packet from an unknown IP address/port combination, fastd will assume that one of its connected peers has moved to a new address and initiate a reconnect by sending a handshake packet. This \"fast reconnect\" avoids having to wait for a session timeout (up to ~90s) until a new connection is established. Even a 1-byte UDP packet just containing the fastd packet type header can trigger a much larger handshake packet (~150 bytes of UDP payload). Including IPv4 and UDP headers, the resulting amplification factor is roughly 12-13. By sending data packets with a spoofed source address to fastd instances reachable on the internet, this amplification of UDP traffic might be used to facilitate a Distributed Denial of Service attack. This vulnerability is fixed in v23.",
  "id": "UBUNTU-CVE-2025-24356",
  "modified": "2025-10-24T05:18:08Z",
  "published": "2025-01-27T18:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-24356"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-24356"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/neocturne/fastd/security/advisories/GHSA-pggg-vpfv-4rcv"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/neocturne/fastd/commit/1f233bee76b722c0b3f9024f2c39c72e9f7e5843"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/neocturne/fastd/commit/3940150e801d0c91460491bec32cbcc5bbc89d5f"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/neocturne/fastd/commit/5f63fcfc18ae9cad023fa463b152d5e14192b5a8"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/neocturne/fastd/commit/9df7e516378441d2d17b89f9db5c27c8312d8f12"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/neocturne/fastd/commit/c1a07b3f2b9066c3713c68547da700b85d60f4f7"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/neocturne/fastd/commit/ce1b79b12dbfa796743b5f3a50789ade965b7023"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/neocturne/fastd/commit/d03a0a17347efb5293e42fde7d982781e90f14ef"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:L",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2025-24356"
  ]
}



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