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TI-2026-21031 Aliases CVE-2026-26017GHSA-c9v3-4pv7-87pr

CoreDNS ACL Bypass

Priority LOW 34CWE-367Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · None · None
Fix status
Partial Red Hat: 3 fixed, 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat.

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0042 36th percentileScored 2026-11-07
Fix Partial coredns (coredns): 1.14.2github.com/coredns/coredns (Go): 1.14.2Red Hat: 3 advisoriesRed Hat: 3 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
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 1.14.21.14.2Patch availableCNA
—github.com/coredns/coredns (Go)before 1.14.21.14.2Patch availableGHSA-c9v3-4pv7-87pr
  • coredns Vendorcoredns Affected before 1.14.2 Fixed in 1.14.2 Patch available CNA
  • github.com/coredns/coredns (Go) Vendor— Affected before 1.14.2 Fixed in 1.14.2 Patch available GHSA-c9v3-4pv7-87pr

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:coredns.io:coredns:*:*:*:*:*:*:*:*before 1.14.2Vulnerablecoredns
  • cpe:2.3:a:coredns.io:coredns:*:*:*:*:*:*:*:* Versions before 1.14.2 Vulnerable ·coredns

Remediation

  • Fix · CNA coredns (coredns) Fixed in 1.14.2
  • Fix · GHSA-c9v3-4pv7-87pr github.com/coredns/coredns (Go) Fixed in 1.14.2 Advisory →

Red Hat 3 advisories

  • RHSA-2026:36873 Released 2026-07-08 · Red Hat rating Important
    Submariner v0.20 security fixes and container updates
    • Red Hat Advanced Cluster Management for Kubernetes 2.13 registry.redhat.io/rhacm2/lighthouse-agent-rhel9, registry.redhat.io/rhacm2/lighthouse-coredns-rhel9, registry.redhat.io/rhacm2/nettest-rhel9 +5
  • 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
  • RHSA-2026:8151 Released 2026-04-14 · Red Hat rating Important
    Submariner v0.22 security fixes and container updates
    • Red Hat Advanced Cluster Management for Kubernetes 2.15 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: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Connectivity Link 1AffectedNo fix yet
Red Hat Advanced Cluster Management for Kubernetes 2.13Fixed RHSA-2026:36873
Red Hat Advanced Cluster Management for Kubernetes 2.14Fixed RHSA-2026:25127
Red Hat Advanced Cluster Management for Kubernetes 2.15Fixed RHSA-2026:8151
Not affected: 4 products
  • Red Hat Advanced Cluster Management for Kubernetes 2.13
  • Red Hat Advanced Cluster Management for Kubernetes 2.14
  • Red Hat Advanced Cluster Management for Kubernetes 2.15
  • Red Hat OpenShift Container Platform 4

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-26017
  2. 2026-10-03 Alias added: GHSA-c9v3-4pv7-87pr

References

Advisory 2

Other 2

  • TI-2026-25615 CoreDNS TSIG authentication bypass on encrypted DNS transports CVSS 4.0HIGH 8.7
  • TI-2026-25384 CoreDNS DoH GET path missing size validation causes CPU and memory amplification 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
See all 15 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences