# CVE-2026-35579: CoreDNS TSIG authentication bypass on gRPC, QUIC, DoH, and DoH3 transports > Unauthenticated attackers can bypass TSIG authentication on gRPC, QUIC, DoH, and DoH3 transports to perform unauthorized zone transfers or DNS updates. - **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/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:** 15 Jul 2026 - **Also known as:** AZL-85730, CLEANSTART-2026-LE40219, CLEANSTART-2026-WT82281, ECHO-a028-dd5c-1ba5, GHSA-vp29-5652-4fw9, GO-2026-5667, MINI-53fq-7vch-9p65, MINI-6vhv-ghcm-q735, MINI-75vx-xq7r-c5r2, MINI-76h9-7qvg-57fr, MINI-77r3-gj8c-hr5c, MINI-89fq-hr22-xwc4, MINI-9gvm-rp54-wjxx, MINI-g34q-hhvc-5rg6, MINI-jm66-hfcr-q2p9, MINI-mpgf-3r26-3497, MINI-p5h2-j9cr-vc82, MINI-pv9r-9wf9-5382, MINI-pvm9-9vq9-5q8x, MINI-qxg8-8vfm-9242, MINI-rc2q-gcxh-gxfg, MINI-rg7f-cgjf-c6w9, MINI-rwqv-cxrf-9x7w, MINI-vpv7-2j87-hj7q, MINI-wp3w-2c5w-xpx6, MINI-xjf6-rxmh-h72q, OESA-2026-3368, OESA-2026-3369, OESA-2026-3370, OESA-2026-3371, OESA-2026-3442 ## What is CVE-2026-35579? CVE-2026-35579 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 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. Weakness: CWE-303 (Incorrect Implementation of Authentication Algorithm), CWE-287 (Improper Authentication) ## Which versions are affected by CVE-2026-35579? 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-2026-35579? Upgrade github.com/coredns/coredns to 1.14.3 or later. ## Is CVE-2026-35579 being exploited? It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-35579 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-2026-33190](https://insights.sbomify.com/CVE-2026-33190/): CoreDNS TSIG authentication bypass on encrypted DNS transports (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-2026-26017](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-2026-35579 and fix it if it is affected. What it is: CVE-2026-35579 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-2026-35579 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-2026-35579/ (Markdown: https://insights.sbomify.com/CVE-2026-35579/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-35579 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-35579 - OSV: https://osv.dev/vulnerability/CVE-2026-35579 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-35579/ Summaries are generated and may contain mistakes; the official description above is the record.