USN-8721-1

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Source
https://ubuntu.com/security/notices/USN-8721-1
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8721-1.json
JSON Data
https://api.osv.dev/v1/vulns/USN-8721-1
Upstream
Related
Published
2026-09-03T12:30:15Z
Modified
2026-09-03T22:56:55.264832476Z
Summary
openssh vulnerabilities
Details

It was discovered that OpenSSH's ssh-agent incorrectly handled interactions between agent locking and the session-bind@openssh.com extension. A remote attacker with access to a forwarded agent connection could possibly use this issue to perform operations that should only be available locally, such as adding tokens or using keys. (CVE-2026-73281)

It was discovered that OpenSSH's ssh client incorrectly handled concurrent remote-forwarding operations. A remote attacker could possibly use this issue to cause a use-after-free condition, resulting in a denial of service or the execution of arbitrary code. (CVE-2026-73282)

It was discovered that OpenSSH's sshd server incorrectly applied the restrict keyword from authorized_keys to tunnel forwarding requests. A local attacker with an authorized key could possibly use this issue to bypass intended tunnel forwarding restrictions. (CVE-2026-73283)

References

Affected packages

Ubuntu:22.04:LTS / openssh

Package

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

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1:8.9p1-3ubuntu0.17

Affected versions

1:8.*
1:8.4p1-6ubuntu2
1:8.7p1-2
1:8.7p1-2build1
1:8.7p1-4
1:8.8p1-1
1:8.9p1-3
1:8.9p1-3ubuntu0.1
1:8.9p1-3ubuntu0.3
1:8.9p1-3ubuntu0.4
1:8.9p1-3ubuntu0.5
1:8.9p1-3ubuntu0.6
1:8.9p1-3ubuntu0.7
1:8.9p1-3ubuntu0.10
1:8.9p1-3ubuntu0.11
1:8.9p1-3ubuntu0.13
1:8.9p1-3ubuntu0.14
1:8.9p1-3ubuntu0.15
1:8.9p1-3ubuntu0.16

Ecosystem specific 

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "openssh-client",
            "binary_version": "1:8.9p1-3ubuntu0.17"
        },
        {
            "binary_name": "openssh-server",
            "binary_version": "1:8.9p1-3ubuntu0.17"
        },
        {
            "binary_name": "openssh-sftp-server",
            "binary_version": "1:8.9p1-3ubuntu0.17"
        },
        {
            "binary_name": "openssh-tests",
            "binary_version": "1:8.9p1-3ubuntu0.17"
        },
        {
            "binary_name": "ssh",
            "binary_version": "1:8.9p1-3ubuntu0.17"
        },
        {
            "binary_name": "ssh-askpass-gnome",
            "binary_version": "1:8.9p1-3ubuntu0.17"
        }
    ]
}

Database specific

cves_map 
{
    "ecosystem": "Ubuntu:22.04:LTS",
    "cves": [
        {
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ],
            "id": "CVE-2026-73281"
        },
        {
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ],
            "id": "CVE-2026-73282"
        },
        {
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ],
            "id": "CVE-2026-73283"
        }
    ]
}
source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8721-1.json"

Ubuntu:24.04:LTS / openssh

Package

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

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1:9.6p1-3ubuntu13.19

Affected versions

1:9.*
1:9.3p1-1ubuntu3
1:9.4p1-1ubuntu1
1:9.6p1-3ubuntu1
1:9.6p1-3ubuntu2
1:9.6p1-3ubuntu11
1:9.6p1-3ubuntu12
1:9.6p1-3ubuntu13
1:9.6p1-3ubuntu13.3
1:9.6p1-3ubuntu13.4
1:9.6p1-3ubuntu13.5
1:9.6p1-3ubuntu13.7
1:9.6p1-3ubuntu13.8
1:9.6p1-3ubuntu13.9
1:9.6p1-3ubuntu13.11
1:9.6p1-3ubuntu13.12
1:9.6p1-3ubuntu13.13
1:9.6p1-3ubuntu13.14
1:9.6p1-3ubuntu13.15
1:9.6p1-3ubuntu13.16
1:9.6p1-3ubuntu13.18

Ecosystem specific 

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "openssh-client",
            "binary_version": "1:9.6p1-3ubuntu13.19"
        },
        {
            "binary_name": "openssh-server",
            "binary_version": "1:9.6p1-3ubuntu13.19"
        },
        {
            "binary_name": "openssh-sftp-server",
            "binary_version": "1:9.6p1-3ubuntu13.19"
        },
        {
            "binary_name": "openssh-tests",
            "binary_version": "1:9.6p1-3ubuntu13.19"
        },
        {
            "binary_name": "ssh",
            "binary_version": "1:9.6p1-3ubuntu13.19"
        },
        {
            "binary_name": "ssh-askpass-gnome",
            "binary_version": "1:9.6p1-3ubuntu13.19"
        }
    ]
}

Database specific

cves_map 
{
    "ecosystem": "Ubuntu:24.04:LTS",
    "cves": [
        {
            "severity": [
                {
                    "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N",
                    "type": "CVSS_V3"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ],
            "id": "CVE-2026-73281"
        },
        {
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ],
            "id": "CVE-2026-73282"
        },
        {
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ],
            "id": "CVE-2026-73283"
        }
    ]
}
source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8721-1.json"

Ubuntu:26.04:LTS / openssh

Package

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

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1:10.2p1-2ubuntu3.6

Affected versions

1:10.*
1:10.0p1-5ubuntu5
1:10.2p1-2ubuntu1
1:10.2p1-2ubuntu3
1:10.2p1-2ubuntu3.2
1:10.2p1-2ubuntu3.4
1:10.2p1-2ubuntu3.5

Ecosystem specific 

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "openssh-client",
            "binary_version": "1:10.2p1-2ubuntu3.6"
        },
        {
            "binary_name": "openssh-client-gssapi",
            "binary_version": "1:10.2p1-2ubuntu3.6"
        },
        {
            "binary_name": "openssh-server",
            "binary_version": "1:10.2p1-2ubuntu3.6"
        },
        {
            "binary_name": "openssh-server-gssapi",
            "binary_version": "1:10.2p1-2ubuntu3.6"
        },
        {
            "binary_name": "openssh-sftp-server",
            "binary_version": "1:10.2p1-2ubuntu3.6"
        },
        {
            "binary_name": "openssh-tests",
            "binary_version": "1:10.2p1-2ubuntu3.6"
        },
        {
            "binary_name": "ssh",
            "binary_version": "1:10.2p1-2ubuntu3.6"
        },
        {
            "binary_name": "ssh-askpass-gnome",
            "binary_version": "1:10.2p1-2ubuntu3.6"
        }
    ]
}

Database specific

cves_map 
{
    "ecosystem": "Ubuntu:26.04:LTS",
    "cves": [
        {
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ],
            "id": "CVE-2026-73281"
        },
        {
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ],
            "id": "CVE-2026-73282"
        },
        {
            "severity": [
                {
                    "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N",
                    "type": "CVSS_V3"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ],
            "id": "CVE-2026-73283"
        }
    ]
}
source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8721-1.json"