Upstream information

CVE-2026-50251 at MITRE

Description

In NLnet Labs Unbound up to and including version 1.25.1, when 'unwanted-reply-threshold' is enabled (set to any value greater than zero), glue records of 0.0.0.0/::0 can short-circuit Unbound, on systems that can direct such traffic, by issuing DNS queries and receiving seemingly unwanted replies since the remote IP does not match the original source IP of 0.0.0.0/::0. This behavior keeps on looping for the glue records and pushing the counter to the configured 'unwanted-reply-threshold' that triggers a defensive cache clear. A malicious actor who controls a delegation that returns in-bailiwick glue of 0.0.0.0/::0 can drive the counter to the limit of 'unwanted-reply-threshold' to the threshold and trigger a cache clean of the message and rrset caches; at will, indefinitely, without sending a single spoofed packet. The iterator uses the 0.0.0.0/::0 glue, and a system that can route this (e.g., Linux kernel routes the datagram over loopback), Unbound's own listener answers from 127.0.0.1. Because of the mismatch of 0.0.0.0 and 127.0.0.1, in this example, Unbound accounts the reply as an unwanted (probably spoofed) answer. The counter resets to zero on every cache flush, so the attack loops forever.

SUSE information

Overall state of this security issue: Pending

This issue is currently rated as having moderate severity.

CVSS v3 Scores
CVSS detail CNA (NLnet Labs) SUSE
Base Score 5.3 5.9
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network Network
Attack Complexity Low High
Privileges Required None None
User Interaction None None
Scope Unchanged Unchanged
Confidentiality Impact None None
Integrity Impact None None
Availability Impact Low High
CVSSv3 Version 3.1 3.1
CVSS v4 Scores
CVSS detail SUSE
Base Score 8.2
Vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Attack Vector Network
Attack Complexity Low
Attack Requirements Present
Privileges Required None
User Interaction None
Vulnerable System Confidentiality Impact None
Vulnerable System Integrity Impact None
Vulnerable System Availability Impact High
Subsequent System Confidentiality Impact None
Subsequent System Integrity Impact None
Subsequent System Availability Impact None
CVSSv4 Version 4.0
SUSE Bugzilla entry: 1271883 [NEW]

SUSE Security Advisories:

List of released packages

Product(s) Fixed package version(s) References
SUSE Linux Enterprise Desktop 15 SP7
SUSE Linux Enterprise Module for Basesystem 15 SP7
SUSE Linux Enterprise Server 15 SP7
SUSE Linux Enterprise Server for SAP Applications 15 SP7
  • libunbound8 >= 1.25.2-150600.23.19.1
  • unbound-anchor >= 1.25.2-150600.23.19.1
  • unbound-devel >= 1.25.2-150600.23.19.1
 Patchnames:
SUSE-SLE-Module-Basesystem-15-SP7-2026-3885 (aarch64,ppc64le,s390x,x86_64)
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-HPC-15-SP4-ESPOS-2026-3884 (aarch64,x86_64)
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-HPC-15-SP4-LTSS-2026-3884 (aarch64,x86_64)
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-HPC-15-SP5-ESPOS-2026-3884 (aarch64,x86_64)
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-HPC-15-SP5-LTSS-2026-3884 (aarch64,x86_64)
SUSE Linux Enterprise Micro 5.5
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Micro-5.5-2026-3884 (aarch64,ppc64le,s390x,x86_64)
SUSE Linux Enterprise Module for Package Hub 15 SP7
  • unbound >= 1.25.2-150600.23.19.1
  • unbound-python >= 1.25.2-150600.23.19.1
 Patchnames:
SUSE-SLE-Module-Packagehub-Subpackages-15-SP7-2026-3885 (aarch64,ppc64le,s390x,x86_64)
SUSE Linux Enterprise Server 15 SP4-LTSS
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-SLES-15-SP4-LTSS-2026-3884 (aarch64,ppc64le,s390x,x86_64)
SUSE Linux Enterprise Server 15 SP5-LTSS
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-SLES-15-SP5-LTSS-2026-3884 (aarch64,ppc64le,s390x,x86_64)
SUSE Linux Enterprise Server 15 SP6-LTSS
  • libunbound8 >= 1.25.2-150600.23.19.1
  • unbound-anchor >= 1.25.2-150600.23.19.1
  • unbound-devel >= 1.25.2-150600.23.19.1
 Patchnames:
SUSE-SLE-Product-SLES-15-SP6-LTSS-2026-3885 (aarch64,ppc64le,s390x,x86_64)
SUSE Linux Enterprise Server 16.0
SUSE Linux Enterprise Server for SAP applications 16.0
  • libunbound8 >= 1.25.2-160000.1.1
  • python3-unbound >= 1.25.2-160000.1.1
  • unbound >= 1.25.2-160000.1.1
  • unbound-anchor >= 1.25.2-160000.1.1
  • unbound-devel >= 1.25.2-160000.1.1
 Patchnames:
SUSE-SLES-16.0-1446 (aarch64,ppc64le,s390x,x86_64)
SUSE Linux Enterprise Server for SAP Applications 15 SP4
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-SLES_SAP-15-SP4-2026-3884 (ppc64le,x86_64)
SUSE Linux Enterprise Server for SAP Applications 15 SP5
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-SLES_SAP-15-SP5-2026-3884 (ppc64le,x86_64)
SUSE Linux Enterprise Server for SAP Applications 15 SP6
  • libunbound8 >= 1.25.2-150600.23.19.1
  • unbound-anchor >= 1.25.2-150600.23.19.1
  • unbound-devel >= 1.25.2-150600.23.19.1
 Patchnames:
SUSE-SLE-Product-SLES_SAP-15-SP6-2026-3885 (ppc64le,x86_64)
SUSE Linux Micro 6.0
  • libunbound8 >= 1.25.2-1.1
  • unbound-anchor >= 1.25.2-1.1
 Patchnames:
SUSE-SLE-Micro-6.0-864 (aarch64,s390x,x86_64)
SUSE Linux Micro 6.1
  • libunbound8 >= 1.25.2-slfo.1.1_1.1
  • unbound-anchor >= 1.25.2-slfo.1.1_1.1
 Patchnames:
SUSE-SLE-Micro-6.1-686 (aarch64,ppc64le,s390x,x86_64)
SUSE Linux Micro 6.2
  • libunbound8 >= 1.25.2-160000.1.1
  • unbound-anchor >= 1.25.2-160000.1.1
 Patchnames:
SUSE-SL-Micro-6.2-1446 (aarch64,ppc64le,s390x,x86_64)
SUSE Manager Proxy LTS 4.3
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-SUSE-Manager-Proxy-4.3-LTS-2026-3884 (x86_64)
SUSE Manager Retail Branch Server LTS 4.3
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-SUSE-Manager-Retail-Branch-Server-4.3-LTS-2026-3884 (x86_64)
SUSE Manager Server LTS 4.3
  • libunbound8 >= 1.25.2-150100.10.28.1
  • unbound-anchor >= 1.25.2-150100.10.28.1
  • unbound-devel >= 1.25.2-150100.10.28.1
 Patchnames:
SUSE-SLE-Product-SUSE-Manager-Server-4.3-LTS-2026-3884 (ppc64le,s390x,x86_64)
openSUSE Leap 16.0
  • libunbound8 >= 1.25.2-160000.1.1
  • python3-unbound >= 1.25.2-160000.1.1
  • unbound >= 1.25.2-160000.1.1
  • unbound-anchor >= 1.25.2-160000.1.1
  • unbound-devel >= 1.25.2-160000.1.1
  • unbound-munin >= 1.25.2-160000.1.1
 Patchnames:
openSUSE-Leap-16.0-1446
openSUSE Tumbleweed
  • libunbound8 >= 1.25.2-1.1
  • python3-unbound >= 1.25.2-1.1
  • unbound >= 1.25.2-1.1
  • unbound-anchor >= 1.25.2-1.1
  • unbound-devel >= 1.25.2-1.1
  • unbound-munin >= 1.25.2-1.1
 Patchnames:
openSUSE-Tumbleweed-2026-11380

Status of this issue by product and package

Please note that this evaluation state might be work in progress, incomplete or outdated. Also information for service packs in the LTSS phase is only included for issues meeting the LTSS criteria. If in doubt, feel free to contact us for clarification. The updates are grouped by state of their lifecycle. SUSE product lifecycles are documented on the lifecycle page.

Product(s) Source package State
Products under general support and receiving all security fixes.
SUSE Linux Enterprise Desktop 15 SP7 unbound Released
SUSE Linux Enterprise Micro 5.5 unbound Released
SUSE Linux Enterprise Module for Basesystem 15 SP7 unbound Released
SUSE Linux Enterprise Module for Package Hub 15 SP7 unbound Released
SUSE Linux Enterprise Server 15 SP7 unbound Released
SUSE Linux Enterprise Server 16.0 unbound Released
SUSE Linux Enterprise Server 16.1 unbound Released
SUSE Linux Enterprise Server for SAP Applications 15 SP7 unbound Released
SUSE Linux Enterprise Server for SAP applications 16.0 unbound Released
SUSE Linux Enterprise Server for SAP applications 16.1 unbound Released
SUSE Linux Micro 6.0 unbound Released
SUSE Linux Micro 6.1 unbound Released
SUSE Linux Micro 6.2 unbound Released
openSUSE Leap 16.0 unbound Affected
Products under Long Term Service Pack support and receiving important and critical security fixes.
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS unbound Released
SUSE Linux Enterprise High Performance Computing 15 SP5 unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS unbound Released
SUSE Linux Enterprise Module for Basesystem 15 SP4 unbound Affected
SUSE Linux Enterprise Module for Basesystem 15 SP5 unbound Affected
SUSE Linux Enterprise Module for Basesystem 15 SP6 unbound Affected
SUSE Linux Enterprise Server 15 SP4 unbound Affected
SUSE Linux Enterprise Server 15 SP4-LTSS unbound Released
SUSE Linux Enterprise Server 15 SP5 unbound Affected
SUSE Linux Enterprise Server 15 SP5-LTSS unbound Released
SUSE Linux Enterprise Server 15 SP6 unbound Affected
SUSE Linux Enterprise Server 15 SP6-LTSS unbound Released
SUSE Linux Enterprise Server for SAP Applications 15 SP4 unbound Released
SUSE Linux Enterprise Server for SAP Applications 15 SP5 unbound Released
SUSE Linux Enterprise Server for SAP Applications 15 SP6 unbound Released
Products past their end of life and not receiving proactive updates anymore.
SUSE CaaS Platform 4.0 unbound Affected
SUSE Enterprise Storage 6 unbound Affected
SUSE Enterprise Storage 7 unbound Affected
SUSE Enterprise Storage 7.1 unbound Affected
SUSE Linux Enterprise Desktop 15 SP1 unbound Affected
SUSE Linux Enterprise Desktop 15 SP2 unbound Affected
SUSE Linux Enterprise Desktop 15 SP3 unbound Affected
SUSE Linux Enterprise Desktop 15 SP4 unbound Affected
SUSE Linux Enterprise Desktop 15 SP5 unbound Affected
SUSE Linux Enterprise Desktop 15 SP6 unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP1 unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP2 unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP3 unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP4 unbound Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS unbound Released
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS unbound Released
SUSE Linux Enterprise Module for Basesystem 15 SP1 unbound Affected
SUSE Linux Enterprise Module for Basesystem 15 SP2 unbound Affected
SUSE Linux Enterprise Module for Basesystem 15 SP3 unbound Affected
SUSE Linux Enterprise Module for Package Hub 15 SP3 unbound Affected
SUSE Linux Enterprise Module for Package Hub 15 SP4 unbound Affected
SUSE Linux Enterprise Module for Package Hub 15 SP5 unbound Affected
SUSE Linux Enterprise Module for Package Hub 15 SP6 unbound Affected
SUSE Linux Enterprise Real Time 15 SP2 unbound Affected
SUSE Linux Enterprise Real Time 15 SP3 unbound Affected
SUSE Linux Enterprise Real Time 15 SP4 unbound Affected
SUSE Linux Enterprise Server 15 SP1 unbound Affected
SUSE Linux Enterprise Server 15 SP1-BCL unbound Affected
SUSE Linux Enterprise Server 15 SP1-LTSS unbound Affected
SUSE Linux Enterprise Server 15 SP2 unbound Affected
SUSE Linux Enterprise Server 15 SP2-BCL unbound Affected
SUSE Linux Enterprise Server 15 SP2-LTSS unbound Affected
SUSE Linux Enterprise Server 15 SP3 unbound Affected
SUSE Linux Enterprise Server 15 SP3-BCL unbound Affected
SUSE Linux Enterprise Server 15 SP3-LTSS unbound Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP1 unbound Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP2 unbound Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP3 unbound Affected
SUSE Manager Proxy 4.0 unbound Affected
SUSE Manager Proxy 4.1 unbound Affected
SUSE Manager Proxy 4.2 unbound Affected
SUSE Manager Proxy 4.3 unbound Affected
SUSE Manager Proxy LTS 4.3 unbound Released
SUSE Manager Retail Branch Server 4.0 unbound Affected
SUSE Manager Retail Branch Server 4.1 unbound Affected
SUSE Manager Retail Branch Server 4.2 unbound Affected
SUSE Manager Retail Branch Server 4.3 unbound Affected
SUSE Manager Retail Branch Server LTS 4.3 unbound Released
SUSE Manager Server 4.0 unbound Affected
SUSE Manager Server 4.1 unbound Affected
SUSE Manager Server 4.2 unbound Affected
SUSE Manager Server 4.3 unbound Affected
SUSE Manager Server LTS 4.3 unbound Released
openSUSE Leap 15.3 unbound Affected
openSUSE Leap 15.4 unbound Affected
openSUSE Leap 15.5 unbound Affected
openSUSE Leap 15.6 unbound Released

SUSE Timeline for this CVE

CVE page created: Thu Jul 23 11:39:11 2026
CVE page last modified: Tue Sep 1 11:36:20 2026