UBUNTU-CVE-2026-33278

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Source
https://ubuntu.com/security/CVE-2026-33278
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33278.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-33278
Upstream
  • CVE-2026-33278
Downstream
Related
Published
2026-05-20T00:00:00Z
Modified
2026-05-21T19:45:56.679900713Z
Severity
  • 9.1 (Critical) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/U:Red CVSS Calculator
  • 9.8 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
  • Ubuntu - high
Summary
[none]
Details

NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure.

References

Affected packages

Ubuntu:Pro:16.04:LTS / unbound

Package

Name
unbound
Purl
pkg:deb/ubuntu/unbound?arch=source&distro=esm-infra%2Fxenial

Affected ranges

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

Affected versions

1.*
1.4.22-1ubuntu6
1.5.7-1ubuntu1
1.5.7-1ubuntu2
1.5.8-1ubuntu1
1.5.8-1ubuntu1.1
1.5.8-1ubuntu1.1+esm1
1.5.8-1ubuntu1.1+esm2

Ecosystem specific 

{
    "priority_reason": "Possible remote code execution",
    "binaries": [
        {
            "binary_name": "libunbound2",
            "binary_version": "1.5.8-1ubuntu1.1+esm2"
        },
        {
            "binary_name": "python-unbound",
            "binary_version": "1.5.8-1ubuntu1.1+esm2"
        },
        {
            "binary_name": "unbound",
            "binary_version": "1.5.8-1ubuntu1.1+esm2"
        },
        {
            "binary_name": "unbound-anchor",
            "binary_version": "1.5.8-1ubuntu1.1+esm2"
        },
        {
            "binary_name": "unbound-host",
            "binary_version": "1.5.8-1ubuntu1.1+esm2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33278.json"

Ubuntu:24.04:LTS / unbound

Package

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

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1.19.2-1ubuntu3.8

Affected versions

1.*
1.17.1-2
1.18.0-2ubuntu1
1.18.0-2ubuntu2
1.19.1-1ubuntu1
1.19.2-1ubuntu1
1.19.2-1ubuntu3
1.19.2-1ubuntu3.1
1.19.2-1ubuntu3.2
1.19.2-1ubuntu3.3
1.19.2-1ubuntu3.4
1.19.2-1ubuntu3.5
1.19.2-1ubuntu3.6
1.19.2-1ubuntu3.7

Ecosystem specific 

{
    "priority_reason": "Possible remote code execution",
    "binaries": [
        {
            "binary_name": "libunbound8",
            "binary_version": "1.19.2-1ubuntu3.8"
        },
        {
            "binary_name": "python3-unbound",
            "binary_version": "1.19.2-1ubuntu3.8"
        },
        {
            "binary_name": "unbound",
            "binary_version": "1.19.2-1ubuntu3.8"
        },
        {
            "binary_name": "unbound-anchor",
            "binary_version": "1.19.2-1ubuntu3.8"
        },
        {
            "binary_name": "unbound-host",
            "binary_version": "1.19.2-1ubuntu3.8"
        }
    ],
    "availability": "No subscription required"
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33278.json"

Ubuntu:25.10 / unbound

Package

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

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1.22.0-2ubuntu2.3

Affected versions

1.*
1.22.0-1ubuntu1
1.22.0-2ubuntu1
1.22.0-2ubuntu2
1.22.0-2ubuntu2.1
1.22.0-2ubuntu2.2

Ecosystem specific 

{
    "priority_reason": "Possible remote code execution",
    "binaries": [
        {
            "binary_name": "libunbound8",
            "binary_version": "1.22.0-2ubuntu2.3"
        },
        {
            "binary_name": "python3-unbound",
            "binary_version": "1.22.0-2ubuntu2.3"
        },
        {
            "binary_name": "unbound",
            "binary_version": "1.22.0-2ubuntu2.3"
        },
        {
            "binary_name": "unbound-anchor",
            "binary_version": "1.22.0-2ubuntu2.3"
        },
        {
            "binary_name": "unbound-host",
            "binary_version": "1.22.0-2ubuntu2.3"
        }
    ],
    "availability": "No subscription required"
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33278.json"

Ubuntu:26.04:LTS / unbound

Package

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

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1.24.2-1ubuntu2.1

Affected versions

1.*
1.22.0-2ubuntu2
1.22.0-2ubuntu4
1.24.2-1ubuntu1
1.24.2-1ubuntu2

Ecosystem specific 

{
    "priority_reason": "Possible remote code execution",
    "binaries": [
        {
            "binary_name": "libunbound8",
            "binary_version": "1.24.2-1ubuntu2.1"
        },
        {
            "binary_name": "python3-unbound",
            "binary_version": "1.24.2-1ubuntu2.1"
        },
        {
            "binary_name": "unbound",
            "binary_version": "1.24.2-1ubuntu2.1"
        },
        {
            "binary_name": "unbound-anchor",
            "binary_version": "1.24.2-1ubuntu2.1"
        },
        {
            "binary_name": "unbound-host",
            "binary_version": "1.24.2-1ubuntu2.1"
        }
    ],
    "availability": "No subscription required"
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33278.json"