UBUNTU-CVE-2026-55655

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Source
https://ubuntu.com/security/CVE-2026-55655
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55655.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-55655
Upstream
Published
2026-06-23T04:17:00Z
Modified
2026-09-11T20:51:50Z
Severity
  • 5.0 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N CVSS Calculator
  • 6.1 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
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.

References

Affected packages

Ubuntu:18.04:LTS
openssh-ssh1

Package

Name
openssh-ssh1
Purl
pkg:deb/ubuntu/openssh-ssh1?arch=source&distro=bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:7.*
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": "1:7.5p1-10"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55655.json"
Ubuntu:20.04:LTS
openssh-ssh1

Package

Name
openssh-ssh1
Purl
pkg:deb/ubuntu/openssh-ssh1?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:7.*
1:7.5p1-11build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-11build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55655.json"
Ubuntu:22.04:LTS
openssh-ssh1

Package

Name
openssh-ssh1
Purl
pkg:deb/ubuntu/openssh-ssh1?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:7.*
1:7.5p1-12
1:7.5p1-12build1
1:7.5p1-13

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-13"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55655.json"
Ubuntu:24.04:LTS
openssh-ssh1

Package

Name
openssh-ssh1
Purl
pkg:deb/ubuntu/openssh-ssh1?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:7.*
1:7.5p1-14
1:7.5p1-15
1:7.5p1-15build1
1:7.5p1-16

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-16"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55655.json"
Ubuntu:25.10
openssh

Package

Name
openssh
Purl
pkg:deb/ubuntu/openssh?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:9.*
1:9.9p1-3ubuntu3
1:9.9p1-3ubuntu3.1
1:10.*
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",
            "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"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55655.json"
openssh-ssh1

Package

Name
openssh-ssh1
Purl
pkg:deb/ubuntu/openssh-ssh1?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:7.*
1:7.5p1-17

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-17"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55655.json"
Ubuntu:26.04:LTS
openssh-ssh1

Package

Name
openssh-ssh1
Purl
pkg:deb/ubuntu/openssh-ssh1?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:7.*
1:7.5p1-17
1:7.5p1-18

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "openssh-client-ssh1",
            "binary_version": "1:7.5p1-18"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55655.json"