CVE-2026-33190 CoreDNS TSIG authentication bypass on encrypted DNS transports
Unauthenticated remote clients can bypass TSIG authentication on encrypted DNS transports, accessing restricted resources in CoreDNS deployments using this feature.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33190?
CVE-2026-33190 is a high-severity authentication bypass vulnerability in coredns, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-303
Which versions are affected by CVE-2026-33190?
3 open source packages ship an affected version, including github.com/coredns/coredns. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/coredns/coredns Go | All versions | 1.14.3 |
github.com/coredns/coredns Go | All versions | 1.14.3 |
github.com/coredns/coredns Go | All versions | 1.14.3 |
Products include Coredns.io Coredns.
How do I fix CVE-2026-33190?
Upgrade github.com/coredns/coredns to 1.14.3 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-33190 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33190 exists.
Other vulnerabilities in coredns
- CVE-2026-32934 CoreDNS DNS-over-QUIC unbounded goroutine growth leads to denial of service
- CVE-2026-32936 CoreDNS DoH GET path missing size validation causes CPU and memory amplification
- CVE-2026-33489 CoreDNS transfer plugin subzone ACL bypass via lexicographic zone comparison
- CVE-2026-35579 CoreDNS TSIG authentication bypass on gRPC, QUIC, DoH, and DoH3 transports
- CVE-2026-26017 CoreDNS ACL Bypass
Sources
Also known as AZL-85718, CLEANSTART-2026-DL45562, CLEANSTART-2026-IX62843, ECHO-e8a3-06c3-1392, GHSA-qhmp-q7xh-99rh, GO-2026-5583 and 20 more.