CVE-2026-32936

CoreDNS is a DNS server that chains plugins. In versions prior to 1.14.3, the DNS-over-HTTPS (DoH) GET path accepts oversized dns= query parameter values and performs URL query parsing, base64 decoding, and DNS message unpacking before rejecting the request. Unlike the POST path, which applies a bounded read via http.MaxBytesReader limited to 65536 bytes, the GET path has no equivalent size validation before expensive processing. A remote, unauthenticated attacker can repeatedly send oversized DoH GET requests to force high CPU usage, large transient memory allocations, and elevated garbage-collection pressure, leading to denial of service. This issue has been fixed in version 1.14.3.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/coredns/coredns/releases/tag/v1.14.3	Release Notes
https://github.com/coredns/coredns/security/advisories/GHSA-63cw-r7xf-jmwr	Exploit Mitigation Vendor Advisory
https://github.com/coredns/coredns/security/advisories/GHSA-63cw-r7xf-jmwr	Exploit Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:coredns.io:coredns:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-05-05 20:16

Updated : 2026-07-25 11:10

NVD link : CVE-2026-32936

Mitre link : CVE-2026-32936

CVE.ORG link : CVE-2026-32936

JSON object : View

Products Affected

coredns.io

coredns

CWE

CWE-400

Uncontrolled Resource Consumption

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En versiones anteriores a la 1.14.3, la ruta GET de DNS-over-HTTPS (DoH) acepta valores de par\u00e1metros de consulta 'dns=' sobredimensionados y realiza el an\u00e1lisis de la consulta URL, la decodificaci\u00f3n base64 y el desempaquetado del mensaje DNS antes de rechazar la solicitud. A diferencia de la ruta POST, que aplica una lectura acotada a trav\u00e9s de http.MaxBytesReader limitada a 65536 bytes, la ruta GET no tiene una validaci\u00f3n de tama\u00f1o equivalente antes de un procesamiento costoso. Un atacante remoto no autenticado puede enviar repetidamente solicitudes GET de DoH sobredimensionadas para forzar un alto uso de CPU, grandes asignaciones de memoria transitoria y una presi\u00f3n elevada de recolecci\u00f3n de basura, lo que lleva a una denegaci\u00f3n de servicio. 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