Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Unauthenticated network-reachable crash of a recursive resolver with availability-only impact; attacker controlling the authoritative server can reliably drive the response ordering, supporting AC:L.
Primary rating from Vendor (isc).
CVSS VectorVendor: isc
Lifecycle Timeline
2DescriptionCVE.org
The issue is unexpected program termination based on ordering and/or specific content in responses to queries for CNAME or DNAME, and A records. Specifically, if a client queries for a DNAME and A record below the DNAME to the resolver, and the authoritative server responds positively to the A query but delays the DNAME response and later responds negatively, named may quit unexpectedly. Or, if a client queries for a CNAME and A record for the same name to the resolver, and the authoritative server responds positively to the A query but delays the CNAME response and later responds with a self-referential CNAME, the same failure may occur. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.
AnalysisAI
Remote denial of service in ISC BIND 9 lets an off-path attacker crash a recursive resolver by controlling the timing and content of authoritative responses to paired queries. When a client asks named to resolve a DNAME plus an A record beneath it (or a CNAME plus an A record for the same name) and the attacker-controlled authoritative server answers the A query positively but delays the DNAME/CNAME response before returning a negative or self-referential answer, named hits a fatal assertion and terminates. The flaw is unauthenticated and network-reachable (CVSS 7.5, availability-only); there is no public exploit identified at time of analysis and it is not on CISA KEV.
Technical ContextAI
BIND 9's named is the reference DNS server implementation, here operating in its recursive resolver role. The bug is CWE-617 (Reachable Assertion): a REQUIRE/INSIST-style consistency check inside the resolver's answer-processing logic can be violated by a legal-but-unusual sequence of authoritative answers. DNAME records redirect an entire subtree of the namespace and are normally synthesized into CNAMEs, while CNAME records alias a single name; both interact with the caching and chain-following code that stitches together A-record answers. By ordering the positive A answer ahead of a delayed, then negative or self-referential (CNAME pointing to itself) redirect answer, the attacker drives the resolver into a state its internal invariants did not anticipate, tripping the assertion. The CPE cpe:2.3:a:isc:bind_9 confirms the affected component is the BIND 9 package rather than any downstream distribution wrapper.
RemediationAI
Vendor-released patch: upgrade the 9.20 branch to 9.20.26 (https://downloads.isc.org/isc/bind9/9.20.26); operators on the 9.18 branch or on the -S1 Supported editions should consult the ISC advisory at https://kb.isc.org/docs/cve-2026-12617 for the corresponding fixed release, as the exact 9.18/-S1 fix version is not stated in the available data and should be confirmed with ISC before deployment. If patching cannot be immediate, reduce exposure by restricting recursion to trusted client networks (allow-recursion/allow-query-cache ACLs) so untrusted clients cannot steer the resolver toward attacker-controlled zones - the trade-off is that open or broadly-serving resolvers lose availability to legitimate external clients. Because triggering depends on the resolver querying a malicious authoritative server, response-policy or DNS firewall controls and monitoring named for unexpected assertion-failure exits with automatic restart (process supervision) further limit downtime while you schedule the upgrade.
BIND resolver servers performing DNSSEC validation can be forced into excessive CPU consumption when encountering a mali
Memory exhaustion in BIND 9 resolver allows unauthenticated remote attackers to cause denial of service by querying spec
Memory corruption in ISC BIND 9's DNS-over-HTTPS (DoH) implementation lets remote attackers trigger a use-after-free (CW
DNSSEC validation bypass in ISC BIND 9 resolvers (9.11.0 through 9.21.23 and S-editions) allows an attacker controlling
Denial of service in ISC BIND 9 lets a remote unauthenticated attacker exhaust resolver memory by flooding a DNSSEC-vali
Remote denial of service in ISC BIND 9 lets an attacker crash a validating resolver via a maliciously crafted DNSSEC pro
Denial of service in ISC BIND 9 resolvers (9.20.0-9.20.24, 9.21.0-9.21.23, and 9.20.9-S1-9.20.24-S1) lets remote unauthe
Cache poisoning in ISC BIND 9 recursive resolvers allows an attacker who controls an authoritative zone to inject forged
RPZ policy bypass and remote denial-of-service in ISC BIND 9 resolvers lets unauthenticated attackers defeat Response Po
Denial of service in ISC BIND 9 DNS servers configured with TKEY GSS-API authentication allows remote unauthenticated at
Remote denial of service in ISC BIND 9 named allows unauthenticated attackers to trigger assertion failures and crash th
DNSSEC integrity bypass in ISC BIND 9 enables network-positioned attackers to forge authenticated NXDOMAIN responses by
Same weakness CWE-617 – Reachable Assertion
View allSame technique Information Disclosure
View allVendor StatusVendor
SUSE
Severity: Important| Product | Status |
|---|---|
| SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise Module for Basesystem 15 SP7 | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Fixed |
| SUSE Linux Enterprise Module for Server Applications 15 SP7 | Fixed |
| openSUSE Leap 16.0 | Fixed |
| openSUSE Tumbleweed | Fixed |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Affected |
| SUSE Linux Enterprise Server 16.0 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.0 | Affected |
| SUSE Linux Enterprise Desktop 15 SP7 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | Affected |
| SUSE Linux Enterprise Micro 5.5 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP7 | Affected |
| SUSE Linux Enterprise Server 15 SP7 | Affected |
| SUSE Linux Enterprise Server 16.0 | Affected |
| SUSE Linux Enterprise Server 16.1 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.0 | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.1 | Affected |
| SUSE Manager Client Tools for SLE Micro 5 | Not-Affected |
| SUSE Multi-Linux Manager Client Tools for SLE Micro 5 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 12 SP5 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP6 | Affected |
| SUSE Linux Enterprise Server 12 SP5 | Not-Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | Not-Affected |
| SUSE Linux Enterprise Server 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Affected |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP5 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | Affected |
| SUSE Manager Proxy 4.3 | Not-Affected |
| SUSE Manager Proxy LTS 4.3 | Not-Affected |
| SUSE Manager Retail Branch Server 4.3 | Not-Affected |
| SUSE Manager Retail Branch Server LTS 4.3 | Not-Affected |
| SUSE Manager Server 4.3 | Not-Affected |
| SUSE Manager Server LTS 4.3 | Not-Affected |
| SUSE CaaS Platform 3.0 | Not-Affected |
| SUSE CaaS Platform 4.0 | Not-Affected |
| SUSE Enterprise Storage 6 | Not-Affected |
| SUSE Enterprise Storage 7 | Not-Affected |
| SUSE Enterprise Storage 7.1 | Not-Affected |
| SUSE Linux Enterprise Desktop 12 SP1 | Not-Affected |
| SUSE Linux Enterprise Desktop 12 SP2 | Not-Affected |
| SUSE Linux Enterprise Desktop 12 SP3 | Not-Affected |
| SUSE Linux Enterprise Desktop 12 SP4 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP6 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 12 SP1 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 12 SP2 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 12 SP3 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 12 SP4 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15-LTSS | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Point of Sale 12 SP2-CLIENT | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Server 12 SP1 | Not-Affected |
| SUSE Linux Enterprise Server 12 SP1-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 12 SP2 | Not-Affected |
| SUSE Linux Enterprise Server 12 SP2-BCL | Not-Affected |
| SUSE Linux Enterprise Server 12 SP2-ESPOS | Not-Affected |
| SUSE Linux Enterprise Server 12 SP2-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 12 SP3 | Not-Affected |
| SUSE Linux Enterprise Server 12 SP3-BCL | Not-Affected |
| SUSE Linux Enterprise Server 12 SP3-ESPOS | Not-Affected |
| SUSE Linux Enterprise Server 12 SP3-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 12 SP4 | Not-Affected |
| SUSE Linux Enterprise Server 12 SP4-ESPOS | Not-Affected |
| SUSE Linux Enterprise Server 12 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15-LTSS | Not-Affected |
| SUSE Linux Enterprise Server for Raspberry Pi 12 SP2 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP1 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP2 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP3 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP4 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Software Development Kit 12 SP1 | Not-Affected |
| SUSE Linux Enterprise Software Development Kit 12 SP2 | Not-Affected |
| SUSE Linux Enterprise Software Development Kit 12 SP3 | Not-Affected |
| SUSE Linux Enterprise Software Development Kit 12 SP4 | Not-Affected |
| SUSE Linux Enterprise Software Development Kit 12 SP5 | Not-Affected |
| SUSE Manager Proxy 4.0 | Not-Affected |
| SUSE Manager Proxy 4.1 | Not-Affected |
| SUSE Manager Proxy 4.2 | Not-Affected |
| SUSE Manager Retail Branch Server 4.0 | Not-Affected |
| SUSE Manager Retail Branch Server 4.1 | Not-Affected |
| SUSE Manager Retail Branch Server 4.2 | Not-Affected |
| SUSE Manager Server 4.0 | Not-Affected |
| SUSE Manager Server 4.1 | Not-Affected |
| SUSE Manager Server 4.2 | Not-Affected |
| SUSE OpenStack Cloud 7 | Not-Affected |
| SUSE OpenStack Cloud 8 | Not-Affected |
| SUSE OpenStack Cloud 9 | Not-Affected |
| SUSE OpenStack Cloud Crowbar 8 | Not-Affected |
| SUSE OpenStack Cloud Crowbar 9 | Not-Affected |
| openSUSE Leap 15.3 | Not-Affected |
| openSUSE Leap 15.4 | Not-Affected |
| openSUSE Leap 15.5 | Not-Affected |
| openSUSE Leap 15.6 | Affected |
| SUSE Multi Linux Manager Tools Beta SLE-Micro-5 | Not-Affected |
| SUSE Multi Linux Manager Tools SLE-Micro-5 | Not-Affected |
| suse/bind | Affected |
| suse/bind:9 | Affected |
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-47711
GHSA-cc7q-gqfw-hrm4