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openvpn — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2020-11810

An issue was discovered in OpenVPN 2.4.x before 2.4.9. An attacker can inject a data channel v2 (P_DATA_V2) packet using a victim's peer-id. Normally such packets are dropped, but if this packet arrives before the data channel crypto parameters have been initialized, the victim's connection will be dropped. This requires careful timing due to the small time window (usually within a few seconds) between the victim client connection starting and the server PUSH_REPLY response back to the client. This attack will only work if Negotiable Cipher Parameters (NCP) is in use.

Products
openvpn
Affected versions
Not specified
Fixed versions
2.4.9-1
CVEs
CVE-2020-11810
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 13:00 UTC · Revision 1

Source evidence

DEBIAN-CVE-2020-11810

core-osv · Original source

Published 27 Apr 2020, 15:15 UTC

An issue was discovered in OpenVPN 2.4.x before 2.4.9. An attacker can inject a data channel v2 (P_DATA_V2) packet using a victim's peer-id. Normally such packets are dropped, but if this packet arrives before the data channel crypto parameters have been initialized, the victim's connection will be dropped. This requires careful timing due to the small time window (usually within a few seconds) between the victim client connection starting and the server PUSH_REPLY response back to the client. This attack will only work if Negotiable Cipher Parameters (NCP) is in use.

osv:DEBIAN-CVE-2020-11810

openvpn

Fixed versions: 2.4.9-1

openvpn

Fixed versions: 2.4.9-1

openvpn

Fixed versions: 2.4.9-1

Complete source record
{
  "id": "6b3da383b2aad471770aa4da4f9d24ae36087c6bb6d976d684eae0b2c821c466",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2020-11810",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2020-11810",
    "summary": "An issue was discovered in OpenVPN 2.4.x before 2.4.9. An attacker can inject a data channel v2 (P_DATA_V2) packet using a victim's peer-id. Normally such packets are dropped, but if this packet arrives before the data channel crypto parameters have been initialized, the victim's connection will be dropped. This requires careful timing due to the small time window (usually within a few seconds) between the victim client connection starting and the server PUSH_REPLY response back to the client. This attack will only work if Negotiable Cipher Parameters (NCP) is in use.",
    "evidence": "osv:DEBIAN-CVE-2020-11810",
    "products": [
      {
        "name": {
          "value": "openvpn",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.4.9-1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "openvpn",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.4.9-1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "openvpn",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.4.9-1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "low",
    "structured": {
      "id": "DEBIAN-CVE-2020-11810",
      "aliases": [
        "DEBIAN-CVE-2020-11810"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.4.9-1"
                }
              ]
            }
          ],
          "package": {
            "name": "openvpn",
            "purl": "pkg:deb/debian/openvpn?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-11810.json"
          },
          "ecosystem_specific": {
            "urgency": "low"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.4.9-1"
                }
              ]
            }
          ],
          "package": {
            "name": "openvpn",
            "purl": "pkg:deb/debian/openvpn?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-11810.json"
          },
          "ecosystem_specific": {
            "urgency": "low"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.4.9-1"
                }
              ]
            }
          ],
          "package": {
            "name": "openvpn",
            "purl": "pkg:deb/debian/openvpn?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-11810.json"
          },
          "ecosystem_specific": {
            "urgency": "low"
          }
        }
      ],
      "modified": "2026-10-26T12:01:24.467990715Z",
      "provider": "osv",
      "upstream": [
        "CVE-2020-11810"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2020-11810"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2020-11810",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 451647,
  "published_at": "2020-04-27T15:15:12.407+00:00"
}