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Fencer Vulns
high 7.5

CVE-2026-32936 json

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

published 2026-04-28 6 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-27442 , GHSA-63cw-r7xf-jmwr , GO-2026-5164

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits
0
none known

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.

Patch / fix

  • go github.com/coredns/coredns 1.14.3
  • coredns.io coredns 1.14.3
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

  • coredns Azure Linux 3.0 1.11.4-17

azure linux advisories AZL-85724

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-2026-32936 updated cvss 7.5

github.com/coredns/coredns: CoreDNS: Denial of Service via oversized DNS-over-HTTPS GET requests

  • Red Hat Advanced Cluster Management for Kubernetes 2.14 rhacm2/lighthouse-agent-rhel9 1780204232, 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 2.14 rhacm2/subctl-rhel9 1780238563, rhacm2/nettest-rhel9 1780241410, rhacm2/submariner-gateway-rhel9 1780204887, rhacm2/submariner-rhel9-operator 1780204322, rhacm2/submariner-globalnet-rhel9 1780204696, rhacm2/submariner-operator-bundle 1780248353, +1 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

0.67% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/coredns/coredns/security/advisories/GHSA-63cw-r7xf-jmwr referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

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

Affected products

  • coredns coredns

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

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.