BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2026
CVE-2026-62309High confidence

CoreDNS: proxyproto plugin panics on PPv2 datagram with non-UDP transport — single 28-byte packet remote DoS

coredns · coredns

Official source article: GitHub GHSA-9RVV-M5G5-WC8R ↗. Check the applicable product and release in the original source.

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Critical, raised one band.upgradedsince 18 Jul 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.66% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs coredns coredns and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-62309 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitygithub.com/coredns/coredns: CoreDNS: Denial of Service via crafted UDP datagram with proxyproto plugin
2 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • rhcl-1/coredns-rhel9 as a component of Red Hat Connectivity Link 1
  • openshift4/ose-coredns-rhel9 as a component of Red Hat OpenShift Container Platform 4
Summary
A flaw was found in CoreDNS. A remote attacker can send a specially crafted 28-byte UDP datagram to a CoreDNS server with the proxyproto plugin enabled. This malformed datagram can cause the CoreDNS process to crash, leading to a denial of service (DoS). The vulnerability arises from improper handling of a PROXY v2 header with a non-UDP transport type, which results in a nil pointer dereference.
Remediation
For release note details, see the upstream Submariner release notes: https://submariner.io/community/releases/ Downstream-specific issues resolved: * ACM-30182 * ACM-32385 * ACM-34578 * ACM-34651 * ACM-34693 * ACM-36281 * ACM-36898 * ACM-36899 * ACM-36907 * ACM-36909 * ACM-36910 * ACM-36911 * ACM-36912 * ACM-36927 * ACM-38289 * ACM-38295 * ACM-38315 * ACM-38320 * ACM-38322 * ACM-38330 * ACM-38357 * ACM-38360 * ACM-38447 * ACM-38448 * ACM-38449 * ACM-38450 * ACM-38451 * ACM-38452 * ACM-38453 * ACM-38466 * ACM-38494 * ACM-38495 * ACM-38496 * ACM-38497 * ACM-38499 * ACM-38500 * ACM-38513 * ACM-38515 * ACM-38519 * ACM-38520 * ACM-38533 * ACM-38538 * ACM-38542 * ACM-38546 * ACM-39374 * ACM-39382 * ACM-39384 * ACM-39385 * ACM-39510 * ACM-39511 * ACM-39568 * ACM-40464 * ACM-41039 * ACM-42640 For more details, see the Red Hat Advanced Cluster Management for Kubernetes documentation: https://docs.redhat.com/documentation/en-us/red_hat_advanced_cluster_management_for_kubernetes/2.17/
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-45019

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

CoreDNS is a DNS server written in Go. Prior to 1.14.4, a single 28-byte UDP datagram can crash the CoreDNS process when the proxyproto plugin is enabled because plugin/pkg/proxyproto/proxyproto.go PacketConn.ReadFrom handles a PROXY v2 header with non-UDP transport such as family byte 0x11, reassigns addr from a nil readFrom result after parseProxyProtocol errors, and calls addr.String() in the warning log before ServeDNS recovery applies. This issue is fixed in version 1.14.4.

What

CoreDNS is a DNS server written in Go. Prior to 1.14.4, a single 28-byte UDP datagram can crash the CoreDNS process when the proxyproto plugin is enabled because plugin/pkg/proxyproto/proxyproto.go PacketConn.ReadFrom handles a PROXY v2 header with non-UDP transport such as family byte 0x11, reassigns addr from a nil readFrom result after parseProxyProtocol errors, and calls addr.String() in the warning log before ServeDNS recovery applies. This issue is fixed in version 1.14.4.

Why

The product dereferences a pointer that it expects to be valid but is NULL.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

CoreDNS is a DNS server written in Go. Prior to 1.14.4, a single 28-byte UDP datagram can crash the CoreDNS process when the proxyproto plugin is enabled because plugin/pkg/proxyproto/proxyproto.go PacketConn.ReadFrom handles a PROXY v2 header with non-UDP transport such as family byte 0x11, reassigns addr from a nil readFrom result after parseProxyProtocol errors, and calls addr.String() in the warning log before ServeDNS recovery applies. This issue is fixed in version 1.14.4.

Why

The product dereferences a pointer that it expects to be valid but is NULL.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → NULL Pointer Dereference → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-476 ↗

CWE-476: NULL Pointer Dereference. The product dereferences a pointer that it expects to be valid but is NULL.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of serviceCWE-476Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2026-2271CoreDNS: Mehrere Schwachstellen ermöglichen Denial of Service

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in CoreDNS ausnutzen, um einen Denial of Service Angriff durchzuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260722Security Bulletin 22 Jul 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 22 Jul 2026, published on 22 July 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-024836The CoreDNS AuthorsのCoreDNSにおけるNULL ポインタデリファレンスに関する脆弱性

CoreDNSはGoで書かれたDNSサーバーです。バージョン1.14.4以前では、proxyprotoプラグインが有効な場合に、28バイトの単一UDPデータグラムがCoreDNSプロセスをクラッシュさせる可能性がありました。これはplugin/pkg/proxyproto/proxyproto.goのPacketConn.ReadFromが、ファミリーバイト0x11のようなUDP以外のトランスポートを持つPROXY v2ヘッダーを処理し、その後parseProxyProtocolでエラーが発生した際にnilのreadFrom結果からaddrを再割り当てし、ServeDNSのリカバリが適用される前に警告ログでaddr.String()を呼び出してしまうためです。この問題はバージョン1.14.4で修正されています。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
Action
For release note details, see the upstream Submariner release notes: https://submariner.io/community/releases/ Downstream-specific issues resolved: * ACM-30182 * ACM-32385 * ACM-34578 * ACM-34651 * ACM-34693 * ACM-36281 * ACM-36898 * ACM-36899 * ACM-36907 * ACM-36909 * ACM-36910 * ACM-36911 * ACM-36912 * ACM-36927 * ACM-38289 * ACM-38295 * ACM-38315 * ACM-38320 * ACM-38322 * ACM-38330 * ACM-38357 * ACM-38360 * ACM-38447 * ACM-38448 * ACM-38449 * ACM-38450 * ACM-38451 * ACM-38452 * ACM-38453 * ACM-38466 * ACM-38494 * ACM-38495 * ACM-38496 * ACM-38497 * ACM-38499 * ACM-38500 * ACM-38513 * ACM-38515 * ACM-38519 * ACM-38520 * ACM-38533 * ACM-38538 * ACM-38542 * ACM-38546 * ACM-39374 * ACM-39382 * ACM-39384 * ACM-39385 * ACM-39510 * ACM-39511 * ACM-39568 * ACM-40464 * ACM-41039 * ACM-42640 For more details, see the Red Hat Advanced Cluster Management for Kubernetes documentation: https://docs.redhat.com/documentation/en-us/red_hat_advanced_cluster_management_for_kubernetes/2.17/
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 16 Jul 2026 · Last source change 18 Jul 2026, 03:14 UTC · CWE-476 · NULL Pointer Dereference

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-45019
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    rhacm2/lighthouse-agent-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; rhcl-1/coredns-rhel9 as a component of Red Hat Connectivity Link 1; openshift4/ose-coredns-rhel9 as a component of Red Hat OpenShift Container Platform 4 · Fixed: registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:321dc468744626a9542c344381f9db454d7cbc7a69e3a925365ce1d8ae8ca474_arm64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17; registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:4b0e567a6b91e16899ad070e6ebe366885e5c2f333ed5f55cfa7e2bd8fc98565_ppc64le as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17; registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:7977035d3755e95121062d90a386a6b23af5d394dacb7c5e622098d70285e1d3_amd64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17; registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:d58913107527d89b998ea945f7aa164ee8ca67de994965e7aa08dc659f4dd818_s390x as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17
    After
    rhcl-1/coredns-rhel9 as a component of Red Hat Connectivity Link 1; openshift4/ose-coredns-rhel9 as a component of Red Hat OpenShift Container Platform 4 · Fixed: registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:321dc468744626a9542c344381f9db454d7cbc7a69e3a925365ce1d8ae8ca474_arm64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17; registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:4b0e567a6b91e16899ad070e6ebe366885e5c2f333ed5f55cfa7e2bd8fc98565_ppc64le as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17; registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:7977035d3755e95121062d90a386a6b23af5d394dacb7c5e622098d70285e1d3_amd64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17; registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:d58913107527d89b998ea945f7aa164ee8ca67de994965e7aa08dc659f4dd818_s390x as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17
    Red Hat Product Security ↗
  2. Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-62309 to remediation: access.redhat.com/CVE-2026-62309.
    Before
    remediation: access.redhat.com/CVE-2026-62309
    After
    remediation: access.redhat.com/CVE-2026-62309
    Red Hat Product Security ↗
  3. Remediation statusRemediation status changed from Mitigation available to Patch available.
    Before
    Mitigation available
    After
    Patch available
    Red Hat Product Security ↗
  4. Affected versionsThe structured affected or fixed version information changed.
    Before
    rhacm2/lighthouse-agent-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; rhacm2/lighthouse-coredns-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; rhcl-1/coredns-rhel9 as a component of Red Hat Connectivity Link 1; openshift4/ose-coredns-rhel9 as a component of Red Hat OpenShift Container Platform 4
    After
    rhacm2/lighthouse-agent-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; rhcl-1/coredns-rhel9 as a component of Red Hat Connectivity Link 1; openshift4/ose-coredns-rhel9 as a component of Red Hat OpenShift Container Platform 4 · Fixed: registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:321dc468744626a9542c344381f9db454d7cbc7a69e3a925365ce1d8ae8ca474_arm64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17; registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:4b0e567a6b91e16899ad070e6ebe366885e5c2f333ed5f55cfa7e2bd8fc98565_ppc64le as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17; registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:7977035d3755e95121062d90a386a6b23af5d394dacb7c5e622098d70285e1d3_amd64 as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17; registry.redhat.io/rhacm2/lighthouse-coredns-rhel9@sha256:d58913107527d89b998ea945f7aa164ee8ca67de994965e7aa08dc659f4dd818_s390x as a component of Red Hat Advanced Cluster Management for Kubernetes 2.17
    Red Hat Product Security ↗
  5. Affected versionsThe structured affected or fixed version information changed.
    Before
    rhacm2/lighthouse-agent-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; rhacm2/lighthouse-coredns-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; rhcl-1/coredns-rhel9 as a component of Red Hat Connectivity Link 1; openshift4/ose-coredns as a component of Red Hat OpenShift Container Platform 4; openshift4/ose-coredns-rhel9 as a component of Red Hat OpenShift Container Platform 4
    After
    rhacm2/lighthouse-agent-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; rhacm2/lighthouse-coredns-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; rhcl-1/coredns-rhel9 as a component of Red Hat Connectivity Link 1; openshift4/ose-coredns-rhel9 as a component of Red Hat OpenShift Container Platform 4
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-45019↗Vendor CSAF · Red Hat Product Security↗Patch or update reference↗Patch or update reference↗Public exploit reference · GitHub GHSA-9RVV-M5G5-WC8R↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-62309 · cve.blacktree.nl