dbcve.org
CorednsApplication · Coredns.io

CVE-2026-35579

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-05
Fix available
A fix is available. Upgrade to 1.14.3 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

CoreDNS versions before 1.14.3 have broken TSIG authentication in gRPC, QUIC, DoH, and DoH3 transports. For gRPC/QUIC, the server checks if a TSIG key name exists but never calls dns.TsigVerify() to validate the HMAC, allowing authentication bypass when the key name matches a configured key. For DoH/DoH3, the DoHWriter.TsigStatus() unconditionally returns nil, treating any request with a TSIG record as authenticated regardless of key name or MAC validity.

MitigationUpgrade CoreDNS to version 1.14.3 or later to fix the TSIG validation. As a workaround, disable gRPC, QUIC, DoH, and DoH3 listeners where TSIG is required, or restrict network access to trusted sources only.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
CorednsApplication
Affected:< 1.14.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check CoreDNS version
    Run `coredns -version` or check the binary metadata to determine the installed version
    Affected if Version is lower than 1.14.3
  2. Identify enabled transports in Corefile
    Examine the CoreDNS configuration file (default /etc/coredns/Corefile or the file specified with -conf) and identify if gRPC, QUIC, DoH, or DoH3 transport plugins are configured. Look for directives like 'grpc', 'quic', 'doh', or 'doh3' in the server blocks
    Affected if Any of gRPC, QUIC, DoH, or DoH3 transports are explicitly enabled in the configuration
  3. Check for TSIG authentication configuration
    Search the Corefile for 'tsig' directives or TSIG key definitions to determine if TSIG is being used for any zone or transfer configuration
    Affected if TSIG is configured for zone transfers or updates in the CoreDNS configuration
  4. Verify transport and TSIG combination
    Review the Corefile to confirm whether TSIG is applied to any endpoint using gRPC, QUIC, DoH, or DoH3 transports. Check if the same server block contains both the transport and a tsig directive
    Affected if TSIG is configured alongside gRPC, QUIC, DoH, or DoH3 on the same server block or endpoint

You are affected if CoreDNS version is below 1.14.3 AND you have gRPC, QUIC, DoH, or DoH3 transports enabled with TSIG authentication configured.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.14.3 or later
Fixed in 1.14.3
Interim mitigation

Upgrade CoreDNS to version 1.14.3 or later to fix the TSIG validation. As a workaround, disable gRPC, QUIC, DoH, and DoH3 listeners where TSIG is required, or restrict network access to trusted sources only.

Recommended fix High confidence

1.14.3

  1. Check the currently running CoreDNS version using `coredns -version` or checking the container/process version
  2. Download CoreDNS version 1.14.3 from the official releases (github.com/coredns/coredns/releases)
  3. Replace the existing coredns binary with version 1.14.3
  4. Restart the CoreDNS service (e.g., `systemctl restart coredns` or restart the container)
  5. Verify the upgrade was successful by checking `coredns -version` shows 1.14.3
  6. If TSIG is used, verify that TSIG authentication is now properly enforced on gRPC, QUIC, DoH, and DoH3 transports

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Coredns Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
16.0 hours of engineering $2,760
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-35579 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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