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Fencer Vulns
high 7.5

CVE-2026-82399 json

CoreDNS: Unauthenticated memory exhaustion in custom transports

published 2026-09-16 53 d ago modified 2026-09-28 42 d ago also EUVD-2026-80987 , GHSA-mrg3-qvqr-jw29 , GO-2026-6507

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. Prior to 1.14.7, the DNS-over-HTTPS, DNS-over-HTTP/3, DNS-over-QUIC, and DNS-over-gRPC request paths in plugin/pkg/doh/doh.go, core/dnsserver/server_quic.go, and core/dnsserver/server_grpc.go call dns.Msg.Unpack on attacker-controlled DNS section counts before dns.DefaultMsgAcceptFunc validates the fixed header. An unauthenticated client can use DNS name compression and excessive section counts to amplify allocation before the plugin chain, so plugin-level rate limiting cannot prevent concurrent requests from exhausting memory and terminating CoreDNS. The ordinary UDP and TCP listeners are not affected because they validate the header first. This issue is fixed in version 1.14.7.

Patch / fix

  • go github.com/coredns/coredns 1.14.7
  • coredns.io coredns 1.14.7
  • coredns Azure Linux 3.0 1.11.4-22

azure linux advisories AZL-101838

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-2026-82399 updated cvss 7.5

github.com/coredns/coredns: CoreDNS: Denial of Service due to unauthenticated memory exhaustion in custom transports

  • Red Hat Connectivity Link 1 rhcl-1/coredns-rhel9 Red Hat OpenShift Container Platform 4 openshift4/ose-coredns-rhel9 Red Hat OpenShift Container Platform 5 openshift5/ose-coredns-rhel9
    affected: workaround, no fix available
  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/lighthouse-agent-rhel9, rhacm2/lighthouse-coredns-rhel9
    not affected: vulnerable code not present
  • Red Hat OpenShift Container Platform 4 openshift4/ose-coredns
    not affected: vulnerable code cannot be controlled by adversary

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
51 d 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-mrg3-qvqr-jw29 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 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
<1.14.7
1.14.7

Affected products

  • coredns coredns

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

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.