LiveActive security incident?Get immediate response
CVE Record

CVE-2026-26018: CoreDNS Loop Detection Denial of Service Vulnerability

CoreDNS is a DNS server that chains plugins. Prior to version 1.14.2, a denial of service vulnerability exists in CoreDNS's loop detection plugin that allows an attacker to crash the DNS server by sending specially crafted DNS queries. The vulnerability stems from the use of a predictable pseudo-random number generator (PRNG) for generating a secret query name, combined with a fatal error handler that terminates the entire process. This issue has been patched in version 1.14.2.

HighCVSS 7.5Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CoreDNS versions before 1.14.2 can be crashed by specially crafted DNS queries against the loop detection plugin. The business impact is DNS outage: dependent applications may fail to resolve names until CoreDNS restarts or is fixed. The supplied sources identify a patch in CoreDNS 1.14.2.

Executive priority

Treat as a high-priority availability issue. It does not indicate data theft or privilege escalation, but DNS failure can create broad application outages. Patch exposed or business-critical CoreDNS deployments first.

Technical view

The flaw combines predictable PRNG generation of a secret query name with a fatal error path that exits the CoreDNS process. CVSS 3.1 is 7.5: network-reachable, low complexity, unauthenticated, no user interaction, with high availability impact only.

Likely exposure

Exposure is likely where CoreDNS before 1.14.2 is deployed and an attacker can send DNS queries to it. Priority is higher for externally reachable DNS services and internal DNS serving critical applications.

Exploitation context

The supplied bundle does not establish active exploitation, and KEV is false. It describes a denial-of-service condition triggered by crafted DNS queries, but does not provide evidence of public exploitation or exploitation at scale.

Researcher notes

Focus validation on CoreDNS versions below 1.14.2 and configurations using the loop detection plugin. Evidence supports availability-only impact. Do not assume affected downstream packages without checking the named vendor advisories or local package metadata.

Mitigation direction

  • Upgrade CoreDNS to version 1.14.2 or later.
  • Apply relevant vendor advisories or errata for packaged CoreDNS builds.
  • Restrict DNS query access to trusted networks where feasible.
  • Monitor CoreDNS crashes and restart loops until remediation is complete.
  • Check vendor guidance for environment-specific mitigations.

Validation and detection

  • Inventory all CoreDNS deployments and record running versions.
  • Confirm whether the loop detection plugin is configured.
  • Identify which CoreDNS instances receive untrusted DNS queries.
  • Verify upgraded systems report CoreDNS 1.14.2 or later.
  • Review vendor errata applicability for Red Hat packaged deployments.
Prepared
Confidence
high
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-1241: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-337: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-400: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-770: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-26018 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
9Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-26018Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPgithub.com/coredns/coredns: CoreDNS: Denial of Service vulnerability due to predictable pseudo-random number generation
other:Red Hat severity ratingcvssV3_1
  • 2026-03-06T16:01:38.150Z: Reported to Red Hat.
  • 2026-03-06T15:35:50.801Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
corednscoredns< 1.14.2Listed
Weakness

CWE details

CWE-1241CWE-337CWE-400CWE-770

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.