USN-8946-2

USN-8946-1 fixed vulnerabilities in Unbound in Ubuntu 26.04 LTS, Ubuntu 24.04 LTS, Ubuntu 22.04 LTS, Ubuntu 20.04 LTS, Ubuntu 18.04 LTS, Ubuntu 16.04 LTS, and Ubuntu 14.04 LTS. This update provides the corresponding update for Ubuntu 26.10.

Original advisory details:

It was discovered that Unbound incorrectly handled certain TCP connections. A remote attacker could possibly use this issue to cause Unbound to consume resources, leading to a denial of service. This issue only affected Ubuntu 26.04 LTS, Ubuntu 24.04 LTS, Ubuntu 22.04 LTS and Ubuntu 20.04 LTS. (CVE-2026-80225)

It was discovered that Unbound incorrectly handled certain DNS responses. A remote attacker could possibly use this issue to crash Unbound, resulting in a denial of service. (CVE-2026-81634)

It was discovered that Unbound incorrectly handled certain DNS responses during DNSSEC validation. A remote attacker could possibly use this issue to cause Unbound to consume resources, leading to a denial of service. (CVE-2026-85501)

It was discovered that Unbound incorrectly handled outgoing network ports. A remote attacker could possibly use this issue to crash Unbound, resulting in a denial of service. (CVE-2026-50252)

It was discovered that Unbound incorrectly handled certain DNSCrypt packets. A remote attacker could possibly use this issue to crash Unbound, resulting in a denial of service. This issue only affected Ubuntu 26.04 LTS, Ubuntu 24.04 LTS, Ubuntu 22.04 LTS, Ubuntu 20.04 LTS and Ubuntu 18.04 LTS. (CVE-2026-40691)

It was discovered that Unbound incorrectly handled certain cached DNS responses. A remote attacker could possibly use this issue to poison Unbound's cache. This issue only affected Ubuntu 26.04 LTS, Ubuntu 24.04 LTS, Ubuntu 22.04 LTS and Ubuntu 20.04 LTS. (CVE-2026-44690)

It was discovered that Unbound incorrectly handled certain DNS-over-QUIC connections. A remote attacker could possibly use this issue to cause Unbound to consume resources, leading to a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-32665)

It was discovered that Unbound incorrectly handled certain EDNS options. A remote attacker could possibly use this issue to crash Unbound, resulting in a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-55973)

References

Affected packages

Ubuntu:26.10 / unbound

Package

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

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

1.25.1-1ubuntu3.1

Affected versions

1.*

1.24.2-1ubuntu2

1.25.1-1ubuntu1

1.25.1-1ubuntu3

Ecosystem specific

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "libunbound8",
            "binary_version": "1.25.1-1ubuntu3.1"
        },
        {
            "binary_name": "python3-unbound",
            "binary_version": "1.25.1-1ubuntu3.1"
        },
        {
            "binary_name": "unbound",
            "binary_version": "1.25.1-1ubuntu3.1"
        },
        {
            "binary_name": "unbound-anchor",
            "binary_version": "1.25.1-1ubuntu3.1"
        },
        {
            "binary_name": "unbound-host",
            "binary_version": "1.25.1-1ubuntu3.1"
        }
    ]
}

Database specific

cves_map

{
    "cves": [
        {
            "id": "CVE-2026-32665",
            "severity": [
                {
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                    "type": "CVSS_V3"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ]
        },
        {
            "id": "CVE-2026-40691",
            "severity": [
                {
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                    "type": "CVSS_V3"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ]
        },
        {
            "id": "CVE-2026-44690",
            "severity": [
                {
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
                    "type": "CVSS_V3"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ]
        },
        {
            "id": "CVE-2026-50252",
            "severity": [
                {
                    "score": "CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:H/E:P/U:Amber",
                    "type": "CVSS_V4"
                },
                {
                    "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H",
                    "type": "CVSS_V3"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ]
        },
        {
            "id": "CVE-2026-55973",
            "severity": [
                {
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                    "type": "CVSS_V3"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ]
        },
        {
            "id": "CVE-2026-80225",
            "severity": [
                {
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
                    "type": "CVSS_V3"
                },
                {
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                    "type": "CVSS_V3"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ]
        },
        {
            "id": "CVE-2026-81634",
            "severity": [
                {
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                    "type": "CVSS_V3"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ]
        },
        {
            "id": "CVE-2026-85501",
            "severity": [
                {
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
                    "type": "CVSS_V3"
                },
                {
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                    "type": "CVSS_V3"
                },
                {
                    "score": "medium",
                    "type": "Ubuntu"
                }
            ]
        }
    ],
    "ecosystem": "Ubuntu:26.10"
}

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8946-2.json"