High

deskflow — security advisory

Type: advisorySources: OSVAdvisory ID: UBUNTU-CVE-2026-44296

Deskflow is a keyboard and mouse sharing app. Prior to 1.26.0.167, a remote, unauthenticated denial of service (DoS) vulnerability affects Deskflow servers running with TLS enabled (the default). When any TCP peer connects to the listening port and its first bytes do not parse as a valid TLS ClientHello, SecureSocket::secureAccept enters its fatal-error branch and calls Arch::sleep(1) (a blocking 1-second sleep) on the multiplexer worker thread. That thread services every socket on the server, including established TLS clients delivering mouse motion, keyboard events, and clipboard updates. A single failed handshake therefore stalls input delivery to all connected screens for ~1 second, and a sustained drip of malformed connections (≥ 1/s) makes the server effectively unusable while the attack persists. This vulnerability is fixed in 1.26.0.167.

Products: deskflow
Affected versions: 1.20.1+dfsg-1, 1.21.2+dfsg-1, 1.22.0+dfsg-2, 1.22.0+dfsg-3, 1.22.0+dfsg-4, 1.22.0+dfsg-6, 1.22.0+dfsg-7, 1.23.0+dfsg-1, 1.24.0+dfsg-2, 1.25.0+dfsg-2, 1.25.0+dfsg-3, 1.26.0+dfsg-1, 1.26.0+dfsg-3, 1.26.0+dfsg-5ubuntu1, 1.27.0+dfsg-1
Fixed versions: Not specified
CVEs: CVE-2026-44296
Confirmed fixed CVEs: Not specified
Updated in this feed: 31 Oct 2026, 02:13 UTC · Revision 1

Source evidence

UBUNTU-CVE-2026-44296

core-osv · Original source

Published 12 May 2026, 22:16 UTC

osv:UBUNTU-CVE-2026-44296

deskflow

Fixed versions: Not specified

deskflow

Fixed versions: Not specified

deskflow

Fixed versions: Not specified

Complete source record

{
  "id": "18e57867a95435c64e30251dd2b55e4561a64feffb8bf113dab858a93c7c7ea8",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-44296",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-44296",
    "summary": "Deskflow is a keyboard and mouse sharing app. Prior to 1.26.0.167, a remote, unauthenticated denial of service (DoS) vulnerability affects Deskflow servers running with TLS enabled (the default). When any TCP peer connects to the listening port and its first bytes do not parse as a valid TLS ClientHello, SecureSocket::secureAccept enters its fatal-error branch and calls Arch::sleep(1) (a blocking 1-second sleep) on the multiplexer worker thread. That thread services every socket on the server, including established TLS clients delivering mouse motion, keyboard events, and clipboard updates. A single failed handshake therefore stalls input delivery to all connected screens for ~1 second, and a sustained drip of malformed connections (≥ 1/s) makes the server effectively unusable while the attack persists. This vulnerability is fixed in 1.26.0.167.",
    "evidence": "osv:UBUNTU-CVE-2026-44296",
    "products": [
      {
        "name": {
          "value": "deskflow",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.20.1+dfsg-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.21.2+dfsg-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.22.0+dfsg-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.22.0+dfsg-3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.22.0+dfsg-4",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.22.0+dfsg-6",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.22.0+dfsg-7",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.23.0+dfsg-1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "deskflow",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.26.0+dfsg-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.26.0+dfsg-3",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.26.0+dfsg-5ubuntu1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.27.0+dfsg-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "deskflow",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.23.0+dfsg-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.24.0+dfsg-2",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.25.0+dfsg-2",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.25.0+dfsg-3",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.26.0+dfsg-1",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "UBUNTU-CVE-2026-44296",
      "aliases": [
        "UBUNTU-CVE-2026-44296"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "deskflow",
            "purl": "pkg:deb/ubuntu/deskflow?arch=source&distro=questing",
            "ecosystem": "Ubuntu:25.10"
          },
          "versions": [
            "1.20.1+dfsg-1",
            "1.21.2+dfsg-1",
            "1.22.0+dfsg-2",
            "1.22.0+dfsg-3",
            "1.22.0+dfsg-4",
            "1.22.0+dfsg-6",
            "1.22.0+dfsg-7",
            "1.23.0+dfsg-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44296.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "deskflow",
                "binary_version": "1.23.0+dfsg-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "deskflow",
            "purl": "pkg:deb/ubuntu/deskflow?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "1.26.0+dfsg-1",
            "1.26.0+dfsg-3",
            "1.26.0+dfsg-5ubuntu1",
            "1.27.0+dfsg-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44296.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "deskflow",
                "binary_version": "1.27.0+dfsg-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "deskflow",
            "purl": "pkg:deb/ubuntu/deskflow?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "1.23.0+dfsg-1",
            "1.24.0+dfsg-2",
            "1.25.0+dfsg-2",
            "1.25.0+dfsg-3",
            "1.26.0+dfsg-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44296.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "deskflow",
                "binary_version": "1.26.0+dfsg-1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T12:58:20.644020780Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-44296"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-44296",
        "https://www.cve.org/CVERecord?id=CVE-2026-44296",
        "https://github.com/deskflow/deskflow/security/advisories/GHSA-3mxm-cgh2-6448",
        "https://github.com/deskflow/deskflow/commit/329783490bd16774ba903b84212467d20d76bfba"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-44296",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 358565,
  "published_at": "2026-05-12T22:16:00+00:00"
}