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Fencer Vulns
high 7.7

CVE-2026-26017 json

CoreDNS ACL Bypass

published 2026-03-06 8 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-10042 , GHSA-c9v3-4pv7-87pr , GO-2026-4630

cvss
7.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits
0
none known

Summary

CoreDNS is a DNS server that chains plugins. Prior to version 1.14.2, a logical vulnerability in CoreDNS allows DNS access controls to be bypassed due to the default execution order of plugins. Security plugins such as acl are evaluated before the rewrite plugin, resulting in a Time-of-Check Time-of-Use (TOCTOU) flaw. This issue has been patched in version 1.14.2.

Patch / fix

  • go github.com/coredns/coredns 1.14.2
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.13 1782924920, 1782924937
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.14 1780204232, 1780204249
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.15 1774086225
  • govulncheck-vulndb openSUSE Leap 15.6 0.0.20260317T205859-150000.1.152.1

suse advisories SUSE-SU-2026:1042-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
  • coredns openSUSE Leap 16.0 1.14.2-bp160.1.1
  • coredns openSUSE Tumbleweed 1.14.2-1.1

opensuse advisories openSUSE-SU-2026:21483-1openSUSE-SU-2026:20619-1openSUSE-SU-2026:10297-1

  • coredns Azure Linux 3.0 1.11.4-15

azure linux advisories AZL-79497

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-2026-26017 updated cvss 7.7

github.com/coredns/coredns: CoreDNS: DNS access control bypass due to plugin execution order flaw

  • Red Hat Connectivity Link 1 rhcl-1/coredns-rhel9
    affected: workaround, no fix available
  • Red Hat Advanced Cluster Management for Kubernetes 2.13 rhacm2/lighthouse-agent-rhel9 1782924920, rhacm2/lighthouse-coredns-rhel9 1782924937
    fixed: vendor fix RHSA-2026:36873
  • 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 2.15 rhacm2 1774086225
    fixed: vendor fix RHSA-2026:8151
  • Red Hat Advanced Cluster Management for Kubernetes 2.13 rhacm2/subctl-rhel9 1782945263, rhacm2/nettest-rhel9 1782926302, rhacm2/submariner-gateway-rhel9 1782925247, rhacm2/submariner-rhel9-operator 1782933193, rhacm2/submariner-globalnet-rhel9 1782925266, rhacm2/submariner-operator-bundle 1783001304, +1 more 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 2.15 rhacm2 1774084104, rhacm2 1774085848, rhacm2 1774332596, rhacm2 1774372741, rhacm2 1774550347, rhacm2 1774550350, +2 more
    not affected: vulnerable code not present
  • Red Hat OpenShift Container Platform 4 openshift4/ose-coredns-rhel9
    not affected: component not present

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
none
Automatable
no
Technical impact
partial
Assessed
8 mo ago

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
CISA ADP 3.1 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
GitHub 3.1 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
NVD 3.1 6.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
go github.com/coredns/coredns
<1.14.2
1.14.2

Affected products

  • coredns coredns
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.13
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.14
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.15
  • Red Hat Red Hat Connectivity Link 1
  • Red Hat Red Hat OpenShift Container Platform 4

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

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.