UBUNTU-CVE-2026-39155

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Source
https://ubuntu.com/security/CVE-2026-39155
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39155.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-39155
Upstream
  • CVE-2026-39155
Published
2026-07-23T21:17:00Z
Modified
2026-07-29T07:55:20Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

Knot DNS before 3.4.10 and 3.5.x before 3.5.4 contains a vulnerability in mod-onlinesign where the next NSEC owner name can be computed incorrectly. This can create an overly broad authenticated denial interval, allowing downstream validating resolvers using aggressive negative caching to synthesize negative answers for legitimate names and causing resolver-side denial of service.

References

Affected packages

Ubuntu:16.04:LTS
knot

Package

Name
knot
Purl
pkg:deb/ubuntu/knot?arch=source&distro=xenial

Affected ranges

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

Affected versions

2.*
2.0.0-1
2.0.1-4
2.0.1-4build1
2.0.2-1
2.0.2-1build1
2.1.0~rc1-52-gd80ce77-1
2.1.0~rc1-55-gf227348-1
2.1.0-2
2.1.0-3
2.1.1-1
2.1.1-1build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "2.1.1-1build1",
            "binary_name": "knot"
        },
        {
            "binary_version": "2.1.1-1build1",
            "binary_name": "knot-dnsutils"
        },
        {
            "binary_version": "2.1.1-1build1",
            "binary_name": "knot-host"
        },
        {
            "binary_version": "2.1.1-1build1",
            "binary_name": "libdnssec0"
        },
        {
            "binary_version": "2.1.1-1build1",
            "binary_name": "libknot1"
        },
        {
            "binary_version": "2.1.1-1build1",
            "binary_name": "libzscanner0"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39155.json"
Ubuntu:18.04:LTS
knot

Package

Name
knot
Purl
pkg:deb/ubuntu/knot?arch=source&distro=bionic

Affected ranges

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

Affected versions

2.*
2.5.3-3
2.6.0-1
2.6.1-2
2.6.3-1
2.6.4-1
2.6.5-1
2.6.5-3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "2.6.5-3",
            "binary_name": "knot"
        },
        {
            "binary_version": "2.6.5-3",
            "binary_name": "knot-dnsutils"
        },
        {
            "binary_version": "2.6.5-3",
            "binary_name": "knot-host"
        },
        {
            "binary_version": "2.6.5-3",
            "binary_name": "libdnssec5"
        },
        {
            "binary_version": "2.6.5-3",
            "binary_name": "libknot7"
        },
        {
            "binary_version": "2.6.5-3",
            "binary_name": "libzscanner1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39155.json"
Ubuntu:20.04:LTS
knot

Package

Name
knot
Purl
pkg:deb/ubuntu/knot?arch=source&distro=focal

Affected ranges

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

Affected versions

2.*
2.7.6-2
2.7.8-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "2.7.8-1",
            "binary_name": "knot"
        },
        {
            "binary_version": "2.7.8-1",
            "binary_name": "knot-dnsutils"
        },
        {
            "binary_version": "2.7.8-1",
            "binary_name": "knot-host"
        },
        {
            "binary_version": "2.7.8-1",
            "binary_name": "libdnssec6"
        },
        {
            "binary_version": "2.7.8-1",
            "binary_name": "libknot8"
        },
        {
            "binary_version": "2.7.8-1",
            "binary_name": "libzscanner2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39155.json"
Ubuntu:22.04:LTS
knot

Package

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

Affected ranges

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

Affected versions

3.*
3.0.5-1ubuntu1
3.1.4-1ubuntu1
3.1.5-1ubuntu1
3.1.6-1ubuntu1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "3.1.6-1ubuntu1",
            "binary_name": "knot"
        },
        {
            "binary_version": "3.1.6-1ubuntu1",
            "binary_name": "knot-dnsutils"
        },
        {
            "binary_version": "3.1.6-1ubuntu1",
            "binary_name": "knot-host"
        },
        {
            "binary_version": "3.1.6-1ubuntu1",
            "binary_name": "knot-module-dnstap"
        },
        {
            "binary_version": "3.1.6-1ubuntu1",
            "binary_name": "knot-module-geoip"
        },
        {
            "binary_version": "3.1.6-1ubuntu1",
            "binary_name": "libdnssec8"
        },
        {
            "binary_version": "3.1.6-1ubuntu1",
            "binary_name": "libknot12"
        },
        {
            "binary_version": "3.1.6-1ubuntu1",
            "binary_name": "libzscanner4"
        },
        {
            "binary_version": "3.1.6-1ubuntu1",
            "binary_name": "python3-libknot"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39155.json"
Ubuntu:24.04:LTS
knot

Package

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

Affected ranges

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

Affected versions

3.*
3.2.9-1
3.3.2-1
3.3.3-1
3.3.3-2
3.3.4-1
3.3.4-1.1build1
3.3.4-1.1build2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "knot"
        },
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "knot-dnssecutils"
        },
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "knot-dnsutils"
        },
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "knot-exporter"
        },
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "knot-host"
        },
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "knot-module-dnstap"
        },
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "knot-module-geoip"
        },
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "libdnssec9t64"
        },
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "libknot14t64"
        },
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "libzscanner4t64"
        },
        {
            "binary_version": "3.3.4-1.1build2",
            "binary_name": "python3-libknot"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39155.json"
Ubuntu:26.04:LTS
knot

Package

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

Affected ranges

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

Affected versions

3.*
3.4.6-2
3.5.1-1
3.5.2-1
3.5.3-1
3.5.3-2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "3.5.3-2",
            "binary_name": "knot"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "knot-dnssecutils"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "knot-dnsutils"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "knot-exporter"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "knot-host"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "knot-keymgr"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "knot-module-dnstap"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "knot-module-geoip"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "libdnssec10"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "libknot16"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "libzscanner5"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "python3-libknot"
        },
        {
            "binary_version": "3.5.3-2",
            "binary_name": "redis-module-knot"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39155.json"