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TI-2026-25384 Aliases CVE-2026-32936GHSA-63cw-r7xf-jmwr

CoreDNS DoH GET path missing size validation causes CPU and memory amplification

Priority HIGH 77CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.

Summary

CoreDNS is a DNS server that chains plugins. In versions prior to 1.14.3, the DNS-over-HTTPS (DoH) GET path accepts oversized dns= query parameter values and performs URL query parsing, base64 decoding, and DNS message unpacking before rejecting the request. Unlike the POST path, which applies a bounded read via http.MaxBytesReader limited to 65536 bytes, the GET path has no equivalent size validation before expensive processing. A remote, unauthenticated attacker can repeatedly send oversized DoH GET requests to force high CPU usage, large transient memory allocations, and elevated garbage-collection pressure, leading to denial of service. This issue has been fixed in version 1.14.3.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00672 52nd 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-63cw-r7xf-jmwr
  • 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-63cw-r7xf-jmwr

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-63cw-r7xf-jmwr 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: Moderate. 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: 3 products
  • 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-2026-32936
  2. 2026-10-03 Alias added: GHSA-63cw-r7xf-jmwr
  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 50th–90th 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-2026-25382 CoreDNS DNS-over-QUIC unbounded goroutine growth leads to denial of service CVSS 4.0HIGH 8.7
  • TI-2026-27682 CoreDNS TSIG authentication bypass on gRPC, QUIC, DoH, and DoH3 transports CVSS 4.0HIGH 8.2
  • 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