Improper Authentication Affecting kubernetes-dns-node-cache package, versions <1.26.8-r3


Severity

Recommended
0.0
critical
0
10

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Threat Intelligence

EPSS
0.09% (26th percentile)

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  • Snyk IDSNYK-WOLFILATEST-KUBERNETESDNSNODECACHE-16423835
  • published5 May 2026
  • disclosed5 May 2026

Introduced: 5 May 2026

NewCVE-2026-35579  (opens in a new tab)
CWE-287  (opens in a new tab)

How to fix?

Upgrade Wolfi kubernetes-dns-node-cache to version 1.26.8-r3 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kubernetes-dns-node-cache package and not the kubernetes-dns-node-cache package as distributed by Wolfi. See How to fix? for Wolfi relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1