CVE-2026-35579
CoreDNS TSIG authentication bypass on gRPC, QUIC, DoH, and DoH3 transports
Description
CoreDNS is a DNS server written in Go. In versions prior to 1.14.3, the gRPC, QUIC, DoH, and DoH3 transport implementations incorrectly handle TSIG authentication. For gRPC and QUIC, the server checks whether the TSIG key name exists in the configuration but never calls dns.TsigVerify() to validate the HMAC. If the key name matches a configured key, the tsigStatus field remains nil and the tsig plugin treats the request as successfully authenticated regardless of the MAC value. For DoH and DoH3, the issue is more severe: the DoHWriter.TsigStatus() method unconditionally returns nil, and the server never inspects the TSIG record at all. Any request containing a TSIG record is treated as authenticated over DoH and DoH3, even if the key name is invalid and the MAC is arbitrary. An unauthenticated network attacker can exploit this to bypass TSIG-protected functionality such as AXFR/IXFR zone transfers, dynamic DNS updates, or other TSIG-gated plugin behavior. The DoH and DoH3 variants have a lower exploitation bar because the attacker does not need to know a valid TSIG key name. This issue has been fixed in version 1.14.3. As a workaround, disable gRPC, QUIC, DoH, and DoH3 listeners where TSIG authentication is required, or restrict network-level access to affected transport ports to trusted sources only.
INFO
Published Date :
May 5, 2026, 9:16 p.m.
Last Modified :
July 24, 2026, 9:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 3.1 | HIGH | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update CoreDNS to version 1.14.3 or later.
- Disable gRPC, QUIC, DoH, DoH3 if TSIG is required.
- Restrict network access to affected ports.
- Ensure TSIG keys are valid and MACs are correct.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-35579.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-35579 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-35579
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-35579 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-35579 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Translated by [email protected]
Jul. 24, 2026
Action Type Old Value New Value Added Translation Title: CoreDNS, Description: CoreDNS es un servidor DNS escrito en Go. En versiones anteriores a la 1.14.3, las implementaciones de transporte gRPC, QUIC, DoH y DoH3 manejan incorrectamente la autenticación TSIG. Para gRPC y QUIC, el servidor verifica si el nombre de la clave TSIG existe en la configuración, pero nunca llama a dns.TsigVerify() para validar el HMAC. Si el nombre de la clave coincide con una clave configurada, el campo tsigStatus permanece nulo y el plugin tsig trata la solicitud como autenticada con éxito, independientemente del valor MAC. Para DoH y DoH3, el problema es más grave: el método DoHWriter.TsigStatus() devuelve nulo incondicionalmente, y el servidor nunca inspecciona el registro TSIG en absoluto. Cualquier solicitud que contenga un registro TSIG se trata como autenticada a través de DoH y DoH3, incluso si el nombre de la clave es inválido y el MAC es arbitrario. Un atacante de red no autenticado puede explotar esto para eludir la funcionalidad protegida por TSIG, como las transferencias de zona AXFR/IXFR, las actualizaciones dinámicas de DNS u otro comportamiento de plugin restringido por TSIG. Las variantes de DoH y DoH3 tienen una barrera de explotación más baja porque el atacante no necesita conocer un nombre de clave TSIG válido. Este problema ha sido corregido en la versión 1.14.3. Como solución alternativa, deshabilite los oyentes gRPC, QUIC, DoH y DoH3 donde se requiera la autenticación TSIG, o restrinja el acceso a nivel de red a los puertos de transporte afectados solo a fuentes confiables. -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jul. 15, 2026
Action Type Old Value New Value Changed Affected [{'cpes': ['cpe:/a:redhat:acm:2.14::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat Advanced Cluster Management for Kubernetes 2.14', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:acm:2'], 'vendor': 'Red Hat', 'product': 'Red Hat Advanced Cluster Management for Kubernetes 2', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:openshift:4'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Container Platform 4', 'defaultStatus': 'unaffected'}] [{'cpes': ['cpe:/a:redhat:acm:2.14::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat Advanced Cluster Management for Kubernetes 2.14', 'versions': [{'status': 'unaffected', 'version': '1780204249', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'rhacm2/lighthouse-coredns-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:acm:2'], 'vendor': 'Red Hat', 'product': 'Red Hat Advanced Cluster Management for Kubernetes 2', 'packageName': 'rhacm2/lighthouse-agent-rhel9', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:openshift:4'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Container Platform 4', 'packageName': 'openshift4/ose-coredns-rhel9', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'unaffected'}] -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jun. 30, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:/a:redhat:acm:2.14::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat Advanced Cluster Management for Kubernetes 2.14', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:acm:2'], 'vendor': 'Red Hat', 'product': 'Red Hat Advanced Cluster Management for Kubernetes 2', 'defaultStatus': 'unaffected'}, {'cpes': ['cpe:/a:redhat:openshift:4'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Container Platform 4', 'defaultStatus': 'unaffected'}] Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Added CWE CWE-303 Added Reference https://access.redhat.com/errata/RHSA-2026:25127 Added Reference https://access.redhat.com/security/cve/CVE-2026-35579 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2466905 Added Reference https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-35579.json -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-35579', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-05-06T14:30:00.602863Z'} -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'coredns', 'product': 'coredns', 'versions': [{'status': 'affected', 'version': '< 1.14.3'}]}] -
Initial Analysis by [email protected]
May. 08, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CPE Configuration OR *cpe:2.3:a:coredns.io:coredns:*:*:*:*:*:*:*:* versions up to (excluding) 1.14.3 Added Reference Type CISA-ADP: https://github.com/coredns/coredns/security/advisories/GHSA-vp29-5652-4fw9 Types: Exploit, Mitigation, Vendor Advisory Added Reference Type GitHub, Inc.: https://github.com/coredns/coredns/security/advisories/GHSA-vp29-5652-4fw9 Types: Exploit, Mitigation, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 06, 2026
Action Type Old Value New Value Added Reference https://github.com/coredns/coredns/security/advisories/GHSA-vp29-5652-4fw9 -
New CVE Received by [email protected]
May. 05, 2026
Action Type Old Value New Value Added Description CoreDNS is a DNS server written in Go. In versions prior to 1.14.3, the gRPC, QUIC, DoH, and DoH3 transport implementations incorrectly handle TSIG authentication. For gRPC and QUIC, the server checks whether the TSIG key name exists in the configuration but never calls dns.TsigVerify() to validate the HMAC. If the key name matches a configured key, the tsigStatus field remains nil and the tsig plugin treats the request as successfully authenticated regardless of the MAC value. For DoH and DoH3, the issue is more severe: the DoHWriter.TsigStatus() method unconditionally returns nil, and the server never inspects the TSIG record at all. Any request containing a TSIG record is treated as authenticated over DoH and DoH3, even if the key name is invalid and the MAC is arbitrary. An unauthenticated network attacker can exploit this to bypass TSIG-protected functionality such as AXFR/IXFR zone transfers, dynamic DNS updates, or other TSIG-gated plugin behavior. The DoH and DoH3 variants have a lower exploitation bar because the attacker does not need to know a valid TSIG key name. This issue has been fixed in version 1.14.3. As a workaround, disable gRPC, QUIC, DoH, and DoH3 listeners where TSIG authentication is required, or restrict network-level access to affected transport ports to trusted sources only. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/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:X Added CWE CWE-287 Added Reference https://github.com/coredns/coredns/security/advisories/GHSA-vp29-5652-4fw9