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Fencer Vulns
high 7.5

CVE-2026-35579 json

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

published 2026-04-28 6 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-27493 , GHSA-vp29-5652-4fw9 , GO-2026-5667

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

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.

Patch / fix

  • go github.com/coredns/coredns 1.14.3
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.14 1780204249
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

  • coredns Azure Linux 3.0 1.11.4-16

azure linux advisories AZL-85730

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-35579 updated cvss 7.5

github.com/coredns/coredns: CoreDNS: Authentication bypass allows unauthorized access to TSIG-protected functionalities

  • Red Hat Advanced Cluster Management for Kubernetes 2.14 rhacm2/lighthouse-coredns-rhel9 1780204249
    fixed: vendor fix RHSA-2026:25127
  • Red Hat Advanced Cluster Management for Kubernetes 2.16 rhacm2/lighthouse-coredns-rhel9 1790670231
    fixed: vendor fix RHSA-2026:85227
  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/lighthouse-agent-rhel9 Red Hat Advanced Cluster Management for Kubernetes 2.14 rhacm2/subctl-rhel9 1780238563, rhacm2/nettest-rhel9 1780241410, rhacm2/lighthouse-agent-rhel9 1780204232, rhacm2/submariner-gateway-rhel9 1780204887, rhacm2/submariner-rhel9-operator 1780204322, rhacm2/submariner-globalnet-rhel9 1780204696, +2 more Red Hat Advanced Cluster Management for Kubernetes 2.16 rhacm2/subctl-rhel9 1790670243, rhacm2/nettest-rhel9 1790702141, rhacm2/lighthouse-agent-rhel9 1790670439, rhacm2/submariner-gateway-rhel9 1790670508, rhacm2/submariner-rhel9-operator 1790670912, rhacm2/submariner-globalnet-rhel9 1790670233, +2 more
    not affected: vulnerable code not present
  • Red Hat OpenShift Container Platform 4 openshift4/ose-coredns-rhel9
    not affected: vulnerable code not in execute path

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.61% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/coredns/coredns/security/advisories/GHSA-vp29-5652-4fw9 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 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
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA 4.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
go github.com/coredns/coredns
<1.14.3
1.14.3

Affected products

  • coredns coredns
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.14
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2
  • Red Hat Red Hat OpenShift Container Platform 4

Classification

Weakness
  • CWE-287 Improper Authentication
  • CWE-303 Incorrect Implementation of Authentication Algorithm

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.