Vulnerability · Published May 5, 2026 · Assigned by GitHub_M

CVE-2026-33190CoreDNS TSIG authentication bypass on encrypted DNS transports

High 8.7

In plain English

A high-severity security flaw in coredns from coredns. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.7High

Exploit odds (30 days)0.4%top 68.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

CoreDNS is a DNS server that chains plugins. In versions prior to 1.14.3, the tsig plugin can be bypassed on non-plain-DNS transports (DoT, DoH, DoH3, DoQ, and gRPC) because it trusts the transport writer's TsigStatus() instead of performing verification itself. The DoH and DoH3 writer's TsigStatus() always returns nil, the DoT server does not set TsigSecret on the dns.Server, and the DoQ and gRPC writers also unconditionally return nil. This allows an unauthenticated remote client to bypass TSIG-based authentication and access resources intended to be restricted behind a tsig require all policy. Plain DNS over TCP and UDP are not affected. This issue has been fixed in version 1.14.3.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/coredns/coredns	1.14.3	GO-2026-5583
Go	github.com/coredns/coredns	1.14.3	GHSA-qhmp-q7xh-99rh

Affected products (as reported)

Vendor	Product	Versions
coredns	coredns	< 1.14.3

Weakness: CWE-303 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

References

https://github.com/coredns/coredns/security/advisories/GHSA-qhmp-q7xh-99rh x_refsource_CONFIRM
https://github.com/coredns/coredns/releases/tag/v1.14.3 x_refsource_MISC