Upstream information
Description
In NLnet Labs Unbound 1.4.22 up to and including 1.25.1, UDP source port is randomized and intended to serve as a secret value that increases the entropy of DNS transactions. When resolver load balancing policies depend on the source port while their outcome is revealed this secrecy is undermined. The vulnerability arises when the load balancing policy is consistent with respect to the incoming source UDP port and IP address while heavily depending on the incoming source UDP port as a randomization source. When the SO_REUSEPORT configuration option is enabled ('so-reuseport: yes') in Unbound (by default), it meets these conditions, making it vulnerable for DNS cache poisoning attacks. Upon startup, Unbound randomly partitions the available UDP source port space into disjoint subsets of (almost) equal size, assigning each subset to a specific worker thread. When an incoming DNS query is received, the kernel's SO_REUSEPORT load balancing mechanism deterministically assigns the query to a socket associated with a particular thread. All outgoing DNS queries generated during the resolution of that request use source ports selected exclusively from the port subset assigned to the corresponding thread. Since these port subsets are disjoint across threads, the source port observed in a resolver's outgoing query to an authoritative name server serves as a reliable indicator of the worker thread that processed the original client query. A malicious actor can acquire the mapping between incoming UDP source ports (for a given fixed source IP address) and Unbound worker threads and leverage it to conduct DNS cache poisoning attacks by effectively lowering the random port population per thread.SUSE information
Overall state of this security issue: Pending
This issue is currently rated as having moderate severity.
| CVSS detail | National Vulnerability Database | SUSE |
|---|---|---|
| Base Score | 9.3 | 5.9 |
| Vector | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N |
| Attack Vector | Adjacent Network | Network |
| Attack Complexity | Low | High |
| Privileges Required | None | None |
| User Interaction | None | None |
| Scope | Changed | Unchanged |
| Confidentiality Impact | None | None |
| Integrity Impact | High | High |
| Availability Impact | High | None |
| CVSSv3 Version | 3.1 | 3.1 |
| CVSS detail | CNA (NLnet Labs) | SUSE |
|---|---|---|
| Base Score | 5.7 | 8.2 |
| Vector | 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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N |
| Attack Vector | Adjacent Network | Network |
| Attack Complexity | Low | Low |
| Attack Requirements | Present | Present |
| Privileges Required | None | None |
| User Interaction | None | None |
| Vulnerable System Confidentiality Impact | None | None |
| Vulnerable System Integrity Impact | High | High |
| Vulnerable System Availability Impact | None | None |
| Subsequent System Confidentiality Impact | None | None |
| Subsequent System Integrity Impact | High | None |
| Subsequent System Availability Impact | High | None |
| CVSSv4 Version | 4.0 | 4.0 |
List of released packages
| Product(s) | Fixed package version(s) | References |
|---|---|---|
| openSUSE Tumbleweed |
| 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 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | unbound | Affected |
| SUSE Linux Enterprise Micro 5.5 | unbound | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | unbound | Affected |
| SUSE Linux Enterprise Module for Package Hub 15 SP7 | unbound | Affected |
| SUSE Linux Enterprise Server 15 SP7 | unbound | 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 | 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 | Affected |
| SUSE Linux Micro 6.1 | unbound | 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 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | unbound | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | unbound | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | unbound | Affected |
| 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 | Affected |
| SUSE Linux Enterprise Server 15 SP5 | unbound | Affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | unbound | Affected |
| SUSE Linux Enterprise Server 15 SP6 | unbound | Affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | unbound | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | unbound | Affected |
| SUSE Manager Proxy 4.3 | unbound | Affected |
| SUSE Manager Proxy LTS 4.3 | unbound | Affected |
| SUSE Manager Retail Branch Server 4.3 | unbound | Affected |
| SUSE Manager Retail Branch Server LTS 4.3 | unbound | Affected |
| SUSE Manager Server 4.3 | unbound | Affected |
| SUSE Manager Server LTS 4.3 | unbound | Affected |
| 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-ESPOS | unbound | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | unbound | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | unbound | Affected |
| 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 Linux Enterprise Server for SAP Applications 15 SP4 | unbound | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | 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 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 Server 4.0 | unbound | Affected |
| SUSE Manager Server 4.1 | unbound | Affected |
| SUSE Manager Server 4.2 | unbound | Affected |
| openSUSE Leap 15.3 | unbound | Affected |
| openSUSE Leap 15.4 | unbound | Affected |
| openSUSE Leap 15.5 | unbound | Affected |
| openSUSE Leap 15.6 | unbound | Affected |
SUSE Timeline for this CVE
CVE page created: Thu Jul 23 11:39:13 2026CVE page last modified: Tue Aug 4 16:34:48 2026