Upstream information

CVE-2026-55973 at MITRE

Description

In NLnet Labs Unbound 1.23.0 up to and including 1.25.1, when 'dns-error-reporting: yes' is set, the EDNS Report-Channel option (code 18) from the last upstream response is read and uses the option's length as the length of the agent domain. When a domain name check is performed on the agent domain, the returned lenght is not used and if the agent domain is followed by garbage, those bytes are moved onto the tail of the synthetic '_er.' report query name. That query name is later used in the iterator via a subquery to send out the DNS Error Report and when Unbound tries to walk that query name during 'find_closest_of_type()', it strips labels using the query name length rather than stopping at the embedded root, walks one byte past it, and feeds the first garbage byte to 'dname_query_hash()' as a label length writing over the stack variable 'labuf'. One ordinary upstream response from a delegated zone the attacker controls is sufficient to terminate the daemon.

SUSE information

Overall state of this security issue: Pending

This issue is currently rated as having important severity.

CVSS v3 Scores
CVSS detail CNA (NLnet Labs) SUSE
Base Score 7.5 7.5
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network Network
Attack Complexity Low Low
Privileges Required None None
User Interaction None None
Scope Unchanged Unchanged
Confidentiality Impact None None
Integrity Impact None None
Availability Impact High High
CVSSv3 Version 3.1 3.1
CVSS v4 Scores
CVSS detail SUSE
Base Score 8.7
Vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Attack Vector Network
Attack Complexity Low
Attack Requirements None
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: 1271874 [NEW]

No SUSE Security Announcements cross referenced.

List of released packages

Product(s) Fixed package version(s) References
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 Not affected
SUSE Linux Enterprise High Performance Computing 15 SP7 unbound Not affected
SUSE Linux Enterprise Micro 5.5 unbound Not affected
SUSE Linux Enterprise Module for Basesystem 15 SP7 unbound Not affected
SUSE Linux Enterprise Module for Package Hub 15 SP7 unbound Not affected
SUSE Linux Enterprise Server 15 SP7 unbound Not affected
SUSE Linux Enterprise Server 16.0 unbound In progress
SUSE Linux Enterprise Server 16.1 unbound Released
SUSE Linux Enterprise Server for SAP Applications 15 SP7 unbound Not affected
SUSE Linux Enterprise Server for SAP applications 16.0 unbound In progress
SUSE Linux Enterprise Server for SAP applications 16.1 unbound Released
SUSE Linux Micro 6.0 unbound Not affected
SUSE Linux Micro 6.1 unbound Not affected
SUSE Linux Micro 6.2 unbound In progress
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 unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP5 unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS unbound Not affected
SUSE Linux Enterprise Module for Basesystem 15 SP4 unbound Not affected
SUSE Linux Enterprise Module for Basesystem 15 SP5 unbound Not affected
SUSE Linux Enterprise Module for Basesystem 15 SP6 unbound Not affected
SUSE Linux Enterprise Server 15 SP4 unbound Not affected
SUSE Linux Enterprise Server 15 SP4-LTSS unbound Not affected
SUSE Linux Enterprise Server 15 SP5 unbound Not affected
SUSE Linux Enterprise Server 15 SP5-LTSS unbound Not affected
SUSE Linux Enterprise Server 15 SP6 unbound Not affected
SUSE Linux Enterprise Server 15 SP6-LTSS unbound Not affected
SUSE Linux Enterprise Server for SAP Applications 15 SP6 unbound Not affected
SUSE Manager Proxy 4.3 unbound Not affected
SUSE Manager Proxy LTS 4.3 unbound Not affected
SUSE Manager Retail Branch Server 4.3 unbound Not affected
SUSE Manager Retail Branch Server LTS 4.3 unbound Not affected
SUSE Manager Server 4.3 unbound Not affected
SUSE Manager Server LTS 4.3 unbound Not affected
Products past their end of life and not receiving proactive updates anymore.
SUSE CaaS Platform 4.0 unbound Not affected
SUSE Enterprise Storage 6 unbound Not affected
SUSE Enterprise Storage 7 unbound Not affected
SUSE Enterprise Storage 7.1 unbound Not affected
SUSE Linux Enterprise Desktop 15 SP1 unbound Not affected
SUSE Linux Enterprise Desktop 15 SP2 unbound Not affected
SUSE Linux Enterprise Desktop 15 SP3 unbound Not affected
SUSE Linux Enterprise Desktop 15 SP4 unbound Not affected
SUSE Linux Enterprise Desktop 15 SP5 unbound Not affected
SUSE Linux Enterprise Desktop 15 SP6 unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP1 unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP2 unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP3 unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS unbound Not affected
SUSE Linux Enterprise High Performance Computing 15 SP6 unbound Not affected
SUSE Linux Enterprise Module for Basesystem 15 SP1 unbound Not affected
SUSE Linux Enterprise Module for Basesystem 15 SP2 unbound Not affected
SUSE Linux Enterprise Module for Basesystem 15 SP3 unbound Not affected
SUSE Linux Enterprise Module for Package Hub 15 SP3 unbound Not affected
SUSE Linux Enterprise Module for Package Hub 15 SP4 unbound Not affected
SUSE Linux Enterprise Module for Package Hub 15 SP5 unbound Not affected
SUSE Linux Enterprise Module for Package Hub 15 SP6 unbound Not affected
SUSE Linux Enterprise Real Time 15 SP2 unbound Not affected
SUSE Linux Enterprise Real Time 15 SP3 unbound Not affected
SUSE Linux Enterprise Real Time 15 SP4 unbound Not affected
SUSE Linux Enterprise Server 15 SP1 unbound Not affected
SUSE Linux Enterprise Server 15 SP1-BCL unbound Not affected
SUSE Linux Enterprise Server 15 SP1-LTSS unbound Not affected
SUSE Linux Enterprise Server 15 SP2 unbound Not affected
SUSE Linux Enterprise Server 15 SP2-BCL unbound Not affected
SUSE Linux Enterprise Server 15 SP2-LTSS unbound Not affected
SUSE Linux Enterprise Server 15 SP3 unbound Not affected
SUSE Linux Enterprise Server 15 SP3-BCL unbound Not affected
SUSE Linux Enterprise Server 15 SP3-LTSS unbound Not affected
SUSE Linux Enterprise Server for SAP Applications 15 SP1 unbound Not affected
SUSE Linux Enterprise Server for SAP Applications 15 SP2 unbound Not affected
SUSE Linux Enterprise Server for SAP Applications 15 SP3 unbound Not affected
SUSE Linux Enterprise Server for SAP Applications 15 SP4 unbound Not affected
SUSE Linux Enterprise Server for SAP Applications 15 SP5 unbound Not affected
SUSE Manager Proxy 4.0 unbound Not affected
SUSE Manager Proxy 4.1 unbound Not affected
SUSE Manager Proxy 4.2 unbound Not affected
SUSE Manager Retail Branch Server 4.0 unbound Not affected
SUSE Manager Retail Branch Server 4.1 unbound Not affected
SUSE Manager Retail Branch Server 4.2 unbound Not affected
SUSE Manager Server 4.0 unbound Not affected
SUSE Manager Server 4.1 unbound Not affected
SUSE Manager Server 4.2 unbound Not affected
openSUSE Leap 15.3 unbound Not affected
openSUSE Leap 15.4 unbound Not affected
openSUSE Leap 15.5 unbound Not affected
openSUSE Leap 15.6 unbound Not affected

SUSE Timeline for this CVE

CVE page created: Thu Jul 23 11:45:00 2026
CVE page last modified: Tue Aug 4 16:36:12 2026