UBUNTU-CVE-2026-5950

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Source
https://ubuntu.com/security/CVE-2026-5950
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-5950
Upstream
Downstream
Related
Published
2026-05-20T00:00:00Z
Modified
2026-07-31T01:59:55Z
Severity
  • 5.3 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions. This issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

References

Affected packages

Ubuntu:18.04:LTS
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=bionic

Affected ranges

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

Affected versions

4.*
4.3.5-3ubuntu2
4.3.5-3ubuntu3
4.3.5-3ubuntu4
4.3.5-3ubuntu5
4.3.5-3ubuntu6
4.3.5-3ubuntu7
4.3.5-3ubuntu7.1
4.3.5-3ubuntu7.2
4.3.5-3ubuntu7.3
4.3.5-3ubuntu7.4

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "isc-dhcp-client",
            "binary_version": "4.3.5-3ubuntu7.4"
        },
        {
            "binary_name": "isc-dhcp-client-ddns",
            "binary_version": "4.3.5-3ubuntu7.4"
        },
        {
            "binary_name": "isc-dhcp-common",
            "binary_version": "4.3.5-3ubuntu7.4"
        },
        {
            "binary_name": "isc-dhcp-relay",
            "binary_version": "4.3.5-3ubuntu7.4"
        },
        {
            "binary_name": "isc-dhcp-server",
            "binary_version": "4.3.5-3ubuntu7.4"
        },
        {
            "binary_name": "isc-dhcp-server-ldap",
            "binary_version": "4.3.5-3ubuntu7.4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json"
Ubuntu:20.04:LTS
bind9-libs

Package

Name
bind9-libs
Purl
pkg:deb/ubuntu/bind9-libs?arch=source&distro=focal

Affected ranges

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

Affected versions

1:9.*
1:9.11.16+dfsg-3~build1
1:9.11.16+dfsg-3~ubuntu1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libbind9-161",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "libdns-export1109",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "libdns1109",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "libirs-export161",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "libirs161",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "libisc-export1105",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "libisc1105",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "libisccc-export161",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "libisccc161",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "libisccfg-export163",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "libisccfg163",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        },
        {
            "binary_name": "liblwres161",
            "binary_version": "1:9.11.16+dfsg-3~ubuntu1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json"
Ubuntu:22.04:LTS
bind9

Package

Name
bind9
Purl
pkg:deb/ubuntu/bind9?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1:9.18.39-0ubuntu0.22.04.4

Affected versions

1:9.*
1:9.16.15-1ubuntu1
1:9.16.15-1ubuntu2
1:9.16.15-1ubuntu3
1:9.18.0-2ubuntu1
1:9.18.0-2ubuntu2
1:9.18.0-2ubuntu3
1:9.18.1-1ubuntu1
1:9.18.1-1ubuntu1.1
1:9.18.1-1ubuntu1.2
1:9.18.1-1ubuntu1.3
1:9.18.12-0ubuntu0.22.04.1
1:9.18.12-0ubuntu0.22.04.2
1:9.18.12-0ubuntu0.22.04.3
1:9.18.18-0ubuntu0.22.04.1
1:9.18.18-0ubuntu0.22.04.2
1:9.18.24-0ubuntu0.22.04.1
1:9.18.28-0ubuntu0.22.04.1
1:9.18.30-0ubuntu0.22.04.1
1:9.18.30-0ubuntu0.22.04.2
1:9.18.39-0ubuntu0.22.04.1
1:9.18.39-0ubuntu0.22.04.2
1:9.18.39-0ubuntu0.22.04.3

Ecosystem specific 

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "bind9",
            "binary_version": "1:9.18.39-0ubuntu0.22.04.4"
        },
        {
            "binary_name": "bind9-dnsutils",
            "binary_version": "1:9.18.39-0ubuntu0.22.04.4"
        },
        {
            "binary_name": "bind9-host",
            "binary_version": "1:9.18.39-0ubuntu0.22.04.4"
        },
        {
            "binary_name": "bind9-libs",
            "binary_version": "1:9.18.39-0ubuntu0.22.04.4"
        },
        {
            "binary_name": "bind9-utils",
            "binary_version": "1:9.18.39-0ubuntu0.22.04.4"
        },
        {
            "binary_name": "bind9utils",
            "binary_version": "1:9.18.39-0ubuntu0.22.04.4"
        },
        {
            "binary_name": "dnsutils",
            "binary_version": "1:9.18.39-0ubuntu0.22.04.4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json"
bind9-libs

Package

Name
bind9-libs
Purl
pkg:deb/ubuntu/bind9-libs?arch=source&distro=jammy

Affected ranges

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

Affected versions

1:9.*
1:9.11.19+dfsg-2.1ubuntu1
1:9.11.19+dfsg-2.1ubuntu2
1:9.11.19+dfsg-2.1ubuntu3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libbind9-161",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "libdns-export1110",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "libdns1110",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "libirs-export161",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "libirs161",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "libisc-export1105",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "libisc1105",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "libisccc-export161",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "libisccc161",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "libisccfg-export163",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "libisccfg163",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        },
        {
            "binary_name": "liblwres161",
            "binary_version": "1:9.11.19+dfsg-2.1ubuntu3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json"
Ubuntu:24.04:LTS
bind9

Package

Name
bind9
Purl
pkg:deb/ubuntu/bind9?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1:9.18.39-0ubuntu0.24.04.5

Affected versions

1:9.*
1:9.18.18-0ubuntu2
1:9.18.21-0ubuntu1
1:9.18.24-0ubuntu3
1:9.18.24-0ubuntu4
1:9.18.24-0ubuntu5
1:9.18.28-0ubuntu0.24.04.1
1:9.18.30-0ubuntu0.24.04.1
1:9.18.30-0ubuntu0.24.04.2
1:9.18.39-0ubuntu0.24.04.1
1:9.18.39-0ubuntu0.24.04.2
1:9.18.39-0ubuntu0.24.04.3

Ecosystem specific 

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "bind9",
            "binary_version": "1:9.18.39-0ubuntu0.24.04.5"
        },
        {
            "binary_name": "bind9-dnsutils",
            "binary_version": "1:9.18.39-0ubuntu0.24.04.5"
        },
        {
            "binary_name": "bind9-host",
            "binary_version": "1:9.18.39-0ubuntu0.24.04.5"
        },
        {
            "binary_name": "bind9-libs",
            "binary_version": "1:9.18.39-0ubuntu0.24.04.5"
        },
        {
            "binary_name": "bind9-utils",
            "binary_version": "1:9.18.39-0ubuntu0.24.04.5"
        },
        {
            "binary_name": "bind9utils",
            "binary_version": "1:9.18.39-0ubuntu0.24.04.5"
        },
        {
            "binary_name": "dnsutils",
            "binary_version": "1:9.18.39-0ubuntu0.24.04.5"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json"
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=noble

Affected ranges

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

Affected versions

4.*
4.4.3-P1-2ubuntu5
4.4.3-P1-4ubuntu1
4.4.3-P1-4ubuntu2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "isc-dhcp-client",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-client-ddns",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-common",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-keama",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-relay",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-server",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-server-ldap",
            "binary_version": "4.4.3-P1-4ubuntu2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json"
Ubuntu:25.10
bind9

Package

Name
bind9
Purl
pkg:deb/ubuntu/bind9?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1:9.20.11-1ubuntu2.4

Affected versions

1:9.*
1:9.20.4-3ubuntu1
1:9.20.4-3ubuntu2
1:9.20.4-3ubuntu3
1:9.20.9-2ubuntu1
1:9.20.10-1ubuntu1
1:9.20.11-1ubuntu1
1:9.20.11-1ubuntu2
1:9.20.11-1ubuntu2.1
1:9.20.11-1ubuntu2.2

Ecosystem specific 

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "bind9",
            "binary_version": "1:9.20.11-1ubuntu2.4"
        },
        {
            "binary_name": "bind9-dnsutils",
            "binary_version": "1:9.20.11-1ubuntu2.4"
        },
        {
            "binary_name": "bind9-host",
            "binary_version": "1:9.20.11-1ubuntu2.4"
        },
        {
            "binary_name": "bind9-libs",
            "binary_version": "1:9.20.11-1ubuntu2.4"
        },
        {
            "binary_name": "bind9-utils",
            "binary_version": "1:9.20.11-1ubuntu2.4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json"
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=questing

Affected ranges

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

Affected versions

4.*
4.4.3-P1-4ubuntu2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "isc-dhcp-client",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-client-ddns",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-common",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-keama",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-relay",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-server",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-server-ldap",
            "binary_version": "4.4.3-P1-4ubuntu2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json"
Ubuntu:26.04:LTS
bind9

Package

Name
bind9
Purl
pkg:deb/ubuntu/bind9?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1:9.20.18-1ubuntu2.1

Affected versions

1:9.*
1:9.20.11-1ubuntu2
1:9.20.11-1ubuntu3
1:9.20.18-1ubuntu1
1:9.20.18-1ubuntu2

Ecosystem specific 

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "bind9",
            "binary_version": "1:9.20.18-1ubuntu2.1"
        },
        {
            "binary_name": "bind9-dnsutils",
            "binary_version": "1:9.20.18-1ubuntu2.1"
        },
        {
            "binary_name": "bind9-host",
            "binary_version": "1:9.20.18-1ubuntu2.1"
        },
        {
            "binary_name": "bind9-libs",
            "binary_version": "1:9.20.18-1ubuntu2.1"
        },
        {
            "binary_name": "bind9-utils",
            "binary_version": "1:9.20.18-1ubuntu2.1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json"
isc-dhcp

Package

Name
isc-dhcp
Purl
pkg:deb/ubuntu/isc-dhcp?arch=source&distro=resolute

Affected ranges

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

Affected versions

4.*
4.4.3-P1-4ubuntu2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "isc-dhcp-client",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-client-ddns",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-common",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-keama",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-relay",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-server",
            "binary_version": "4.4.3-P1-4ubuntu2"
        },
        {
            "binary_name": "isc-dhcp-server-ldap",
            "binary_version": "4.4.3-P1-4ubuntu2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-5950.json"