UBUNTU-CVE-2026-55655 (CVE-2026-55655)

Vulnerability from osv_ubuntu – Published: 2026-06-23 04:17 – Updated: 2026-09-11 18:15 – Source website
VLAI
Details

A flaw was found in OpenSSH. A local unprivileged attacker on a Linux client host can hijack client-side X11 forwarding connections. This is possible by pre-binding the preferred abstract X socket name when X11 forwarding is enabled and a local UNIX-domain X socket is used. A successful attack can compromise the confidentiality of forwarded X11 traffic, including sensitive window contents and input, and may allow some manipulation of the forwarded session.

Severity
5.0 (Medium)
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N
6.1 (Medium)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-10"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "openssh-ssh1",
        "purl": "pkg:deb/ubuntu/openssh-ssh1@1:7.5p1-10?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:7.5p1-8",
        "1:7.5p1-9",
        "1:7.5p1-9build1",
        "1:7.5p1-10"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-11build1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "openssh-ssh1",
        "purl": "pkg:deb/ubuntu/openssh-ssh1@1:7.5p1-11build1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:7.5p1-11build1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-13"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "openssh-ssh1",
        "purl": "pkg:deb/ubuntu/openssh-ssh1@1:7.5p1-13?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:7.5p1-12",
        "1:7.5p1-12build1",
        "1:7.5p1-13"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-16"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "openssh-ssh1",
        "purl": "pkg:deb/ubuntu/openssh-ssh1@1:7.5p1-16?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:7.5p1-14",
        "1:7.5p1-15",
        "1:7.5p1-15build1",
        "1:7.5p1-16"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "openssh-client",
            "binary_version": "1:10.0p1-5ubuntu5.4"
          },
          {
            "binary_name": "openssh-client-gssapi",
            "binary_version": "1:10.0p1-5ubuntu5.4"
          },
          {
            "binary_name": "openssh-server",
            "binary_version": "1:10.0p1-5ubuntu5.4"
          },
          {
            "binary_name": "openssh-server-gssapi",
            "binary_version": "1:10.0p1-5ubuntu5.4"
          },
          {
            "binary_name": "openssh-sftp-server",
            "binary_version": "1:10.0p1-5ubuntu5.4"
          },
          {
            "binary_name": "openssh-tests",
            "binary_version": "1:10.0p1-5ubuntu5.4"
          },
          {
            "binary_name": "ssh",
            "binary_version": "1:10.0p1-5ubuntu5.4"
          },
          {
            "binary_name": "ssh-askpass-gnome",
            "binary_version": "1:10.0p1-5ubuntu5.4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "openssh",
        "purl": "pkg:deb/ubuntu/openssh@1:10.0p1-5ubuntu5.4?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:9.9p1-3ubuntu3",
        "1:9.9p1-3ubuntu3.1",
        "1:10.0p1-5ubuntu2",
        "1:10.0p1-5ubuntu3",
        "1:10.0p1-5ubuntu4",
        "1:10.0p1-5ubuntu5",
        "1:10.0p1-5ubuntu5.1",
        "1:10.0p1-5ubuntu5.4"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-17"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "openssh-ssh1",
        "purl": "pkg:deb/ubuntu/openssh-ssh1@1:7.5p1-17?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:7.5p1-17"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-18"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "openssh-ssh1",
        "purl": "pkg:deb/ubuntu/openssh-ssh1@1:7.5p1-18?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:7.5p1-17",
        "1:7.5p1-18"
      ]
    }
  ],
  "aliases": [],
  "details": "A flaw was found in OpenSSH. A local unprivileged attacker on a Linux client host can hijack client-side X11 forwarding connections. This is possible by pre-binding the preferred abstract X socket name when X11 forwarding is enabled and a local UNIX-domain X socket is used. A successful attack can compromise the confidentiality of forwarded X11 traffic, including sensitive window contents and input, and may allow some manipulation of the forwarded session.",
  "id": "UBUNTU-CVE-2026-55655",
  "modified": "2026-09-11T18:15:25Z",
  "published": "2026-06-23T04:17:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-55655"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-55655"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-55655"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2462250"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-55655"
  ]
}



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