Vulnerability · Published May 5, 2026 · Assigned by GitHub_M
CVE-2026-35579CoreDNS TSIG authentication bypass on gRPC, QUIC, DoH, and DoH3 transports
High 7.5
In plain English
A high-severity improper authentication in coredns from coredns. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/coredns/coredns | 1.14.3 | GHSA-vp29-5652-4fw9 |
| Go | github.com/coredns/coredns | 1.14.3 | GO-2026-5667 |
Affected products (as reported)
Weakness: CWE-287, CWE-303 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
References
- https://github.com/coredns/coredns/security/advisories/GHSA-vp29-5652-4fw9 x_refsource_CONFIRM
- https://access.redhat.com/security/cve/CVE-2026-35579 vdb-entry, x_refsource_REDHAT
- RHBZ#2466905 issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-35579.json x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:25127 vendor-advisory, x_refsource_REDHAT