# 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. - **Severity:** High 8.7 (`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`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 5 May 2026 - **Updated:** 6 May 2026 - **Also known as:** AZL-85718, CLEANSTART-2026-DL45562, CLEANSTART-2026-IX62843, ECHO-e8a3-06c3-1392, GHSA-qhmp-q7xh-99rh, GO-2026-5583, MINI-523p-mr57-3gm6, MINI-53rx-m6mw-pc48, MINI-683c-w5cx-jgm8, MINI-7gj4-4mgc-63w3, MINI-85jr-r69p-v69g, MINI-c56v-5w4w-4v83, MINI-cwqj-4c65-p376, MINI-ffx7-v6j3-h6q9, MINI-fwx6-8x5v-h2wg, MINI-g28v-c779-gmh7, MINI-g98w-h3qw-mf38, MINI-hj9v-4cjj-9gq9, MINI-hphx-rr3f-7cww, MINI-j37f-6vmp-536x, MINI-jw78-68jr-m896, MINI-p3v9-4v5p-h72q, MINI-pjgq-x6g4-j7v4, MINI-v2pg-j5rp-hw7v, MINI-vvxr-rrj2-346c, MINI-w4x8-36wx-5qh2 ## 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 (Incorrect Implementation of Authentication Algorithm) ## 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 | Ecosystem | 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: Coredns.io Coredns. ## How do I fix CVE-2026-33190? Upgrade github.com/coredns/coredns to 1.14.3 or later. ## 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](https://insights.sbomify.com/CVE-2026-32934/): CoreDNS DNS-over-QUIC unbounded goroutine growth leads to denial of service (high 8.7) - [CVE-2026-32936](https://insights.sbomify.com/CVE-2026-32936/): CoreDNS DoH GET path missing size validation causes CPU and memory amplification (high 8.7) - [CVE-2026-33489](https://insights.sbomify.com/CVE-2026-33489/): CoreDNS transfer plugin subzone ACL bypass via lexicographic zone comparison (high 8.2) - [CVE-2026-35579](https://insights.sbomify.com/CVE-2026-35579/): CoreDNS TSIG authentication bypass on gRPC, QUIC, DoH, and DoH3 transports (high 8.2) - [CVE-2026-26017](https://insights.sbomify.com/CVE-2026-26017/): CoreDNS ACL Bypass (high 7.7) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-33190 and fix it if it is affected. What it is: 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. Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33190 exists. Affected packages and fixed versions: - github.com/coredns/coredns (Go): affected all versions; fixed in 1.14.3 - github.com/coredns/coredns (Go): affected all versions; fixed in 1.14.3 - github.com/coredns/coredns (Go): affected all versions; fixed in 1.14.3 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-33190/ (Markdown: https://insights.sbomify.com/CVE-2026-33190/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33190 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33190 - OSV: https://osv.dev/vulnerability/CVE-2026-33190 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-33190/ Summaries are generated and may contain mistakes; the official description above is the record.