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TI-2026-27682 Aliases CVE-2026-35579GHSA-vp29-5652-4fw9

CoreDNS TSIG authentication bypass on gRPC, QUIC, DoH, and DoH3 transports

Priority HIGH 75CWE-287Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
Security bypass
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-287.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00611 49th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed coredns (coredns): 1.14.3github.com/coredns/coredns (Go): 1.14.3Red Hat: 2 advisories

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
corednscorednsbefore 1.14.31.14.3Patch availableCNA
—github.com/coredns/coredns (Go)before 1.14.31.14.3Patch availableGHSA-vp29-5652-4fw9
  • coredns Vendorcoredns Affected before 1.14.3 Fixed in 1.14.3 Patch available CNA
  • github.com/coredns/coredns (Go) Vendor— Affected before 1.14.3 Fixed in 1.14.3 Patch available GHSA-vp29-5652-4fw9

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:coredns.io:coredns:*:*:*:*:*:*:*:*before 1.14.3Vulnerablecoredns
  • cpe:2.3:a:coredns.io:coredns:*:*:*:*:*:*:*:* Versions before 1.14.3 Vulnerable ·coredns

Remediation

  • Fix · CNA coredns (coredns) Fixed in 1.14.3
  • Fix · GHSA-vp29-5652-4fw9 github.com/coredns/coredns (Go) Fixed in 1.14.3 Advisory →

Red Hat 2 advisories

  • RHSA-2026:85227 Released 2026-10-19 · Red Hat rating Important
    Submariner v0.23 security fixes and container updates
    • Red Hat Advanced Cluster Management for Kubernetes 2.16 registry.redhat.io/rhacm2/lighthouse-agent-rhel9, registry.redhat.io/rhacm2/lighthouse-coredns-rhel9, registry.redhat.io/rhacm2/subctl-rhel9 +4
  • RHSA-2026:25127 Released 2026-06-10 · Red Hat rating Important
    Submariner v0.21 security fixes and container updates
    • Red Hat Advanced Cluster Management for Kubernetes 2.14 registry.redhat.io/rhacm2/lighthouse-agent-rhel9, registry.redhat.io/rhacm2/lighthouse-coredns-rhel9, registry.redhat.io/rhacm2/nettest-rhel9 +5

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Advanced Cluster Management for Kubernetes 2.14Fixed RHSA-2026:25127
Red Hat Advanced Cluster Management for Kubernetes 2.16Fixed RHSA-2026:85227
Not affected: 4 products
  • Red Hat Advanced Cluster Management for Kubernetes 2
  • Red Hat Advanced Cluster Management for Kubernetes 2.14
  • Red Hat Advanced Cluster Management for Kubernetes 2.16
  • Red Hat OpenShift Container Platform 4

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-35579
  2. 2026-10-03 Alias added: GHSA-vp29-5652-4fw9
  3. 2026-10-20 Fix available: RHSA-2026:85227 · Red Hat
  4. 2026-10-20 Fix available: Red Hat Advanced Cluster Management for Kubernetes 2.16 · Red Hat
  5. 2026-10-25 EPSS moved to the below the 50th percentile

References

Exploit 1

Advisory 1

Other 2

  • TI-2026-25615 CoreDNS TSIG authentication bypass on encrypted DNS transports CVSS 4.0HIGH 8.7
  • TI-2026-25384 CoreDNS DoH GET path missing size validation causes CPU and memory amplification CVSS 4.0HIGH 8.7
  • TI-2026-25382 CoreDNS DNS-over-QUIC unbounded goroutine growth leads to denial of service CVSS 4.0HIGH 8.7
  • TI-2026-25885 CoreDNS transfer plugin subzone ACL bypass via lexicographic zone comparison CVSS 4.0HIGH 8.2
  • TI-2026-44486 NULL pointer dereference in coredns CVSS 3.1MEDIUM 5.3
  • TI-2026-44995 CoreDNS `k8s_external` headless AXFR can emit an empty transfer batch that panics the `transfer` plugin CVSS 3.1LOW 3.7
See all 15 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences