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Full vulnerability report · 2026
CVE-2026-4890High confidence

CVE-2026-4890

dnsmasq · dnsmasq

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

1 package state
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · standard archivednsmasqVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.2.90-2ubuntu0.3Canonical record ↗Source updated 9 Sept 2026
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-2026-4890 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitydnsmasq: NSEC bitmap parsing infinite loop
7 under investigation

The vendor has not yet reached a final affected or unaffected determination for these products.

  • dnsmasq as a component of Red Hat Enterprise Linux 6
  • dnsmasq-utils as a component of Red Hat Enterprise Linux 6
  • dnsmasq.src as a component of Red Hat Enterprise Linux 6
  • dnsmasq as a component of Red Hat Enterprise Linux 7
  • dnsmasq-utils as a component of Red Hat Enterprise Linux 7
  • dnsmasq.src as a component of Red Hat Enterprise Linux 7
  • openshift/ose-rhel-coreos-8 as a component of Red Hat OpenShift Container Platform 4
Summary
A denial of service vulnerability was discovered in dnsmasq's DNSSEC validation. When parsing NSEC and NSEC3 bitmap records, the window iteration logic fails to account for the 2-byte window header when advancing through the bitmap data. A specially crafted DNS response with a zero-length bitmap can cause an infinite loop, making dnsmasq unresponsive to all queries.
Remediation
For OpenShift Container Platform 4.19 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.19/html/release_notes/ You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags. The sha values for the release are as follows: (For x86_64 architecture) The image digest is sha256:8367df5ccbec71bfd55d827da81c659e301e17073b8a1a47e43d3e201adb4fd1 (For s390x architecture) The image digest is sha256:8eb5fa80e5e92443a0870c876e82b03971051c4285d9f71ef025eea098448dff (For ppc64le architecture) The image digest is sha256:5d7790ac52e357afe0a15363f4eefd505029cc49a3fc147787cc5b96d8bbc666 (For aarch64 architecture) The image digest is sha256:ed4761bb6a0bb26e5250aa36776dbe48d9ccab7fb1a05a253aa6ef2d59d32fde All OpenShift Container Platform 4.19 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshift_container_platform/4.19/html-single/updating_clusters/index#updating-cluster-cli.
Optional official sources

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

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

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-2026-29152

No EUVD known-exploited evidence

A Denial of Service (DoS) vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

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
7.5 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

A Denial of Service (DoS) vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

What

A Denial of Service (DoS) vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

Why

A malformed condition prevents a loop from making progress or terminating, allowing resource exhaustion.

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

A Denial of Service (DoS) vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

Why

A malformed condition prevents a loop from making progress or terminating, allowing resource exhaustion.

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.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Loop with Unreachable Exit Condition ('Infinite Loop') → 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-835 ↗

CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop'). The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

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-835
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-29152Official EUVD mapping

A Denial of Service (DoS) vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

Official EUVD record
BSI · German · WID-SEC-W-2026-1468dnsmasq: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in dnsmasq ausnutzen, um einen Denial-of-Service-Zustand zu verursachen, beliebigen Code mit Root-Rechten auszuführen, vertrauliche Informationen offenzulegen, Daten zu manipulieren und Benutzer auf bösartige Domains umzuleiten

Official advisory
CERT-FR · French · CERTFR-2026-AVI-0986Multiples vulnérabilités dans les produits IBM

d?id=CVE-2026-46243 Référence CVE CVE-2026-46968 https://www.cve.org/CVERecord?id=CVE-2026-46968 Référence CVE CVE-2026-47010 https://www.cve.org/CVERecord?id=CVE-2026-47010 Référence CVE CVE-2026-47021 https://www.cve.org/CVERecord?id=CVE-2026-47021 Référence CVE CVE-2026-47027 https://www.cve.org/CVERecord?id=CVE-2026-47027 Référence CVE CVE-2026-47057 https://www.cve.org/CVERecord?id=CVE-2026-47057 Référence CVE CVE-2026-47058 https://www.cve.org/CVERecord?id=CVE-2026-47058 Référence CVE CVE-2026-47059 https://www.cve.org/CVERecord?id=CVE-2026-47059 Référence CVE CVE-2026-47063 https://www.cve.org/CVERecord?id=CVE-2026-47063 Référence CVE CVE-2026-4890 https://www.cve.org/CVERecord?id=CVE-2026-4890 Référence CVE CVE-2026-4891 https://www.cve.org/CVERecord?id=CVE-2026-4891 Référence CVE CVE-2026-4892 https://www.cve.org/CVERecord?id=CVE-2026-4892 Référence CVE CVE-2026-4893 https://www.cve.org/CVERecord?id=CVE-2026-4893 Référence CVE CVE-2026-48962 https://www.cve.org/CVERecord?id=CVE-2026-48962 Référence CVE CVE-2026-48978 https://www.cve.org/CVERecord?id=CVE-2026-48978 Référence CVE CVE-2026-49268 https://www.cve.org/CVERecord?id=CVE-2026-49268 Référence CVE CVE-2026-49432 https://www.cve.org/CVERecord?id=CVE-2026-49432 Référence CVE CVE-2026-49434 https://www.cve.org/CVERecord?id=CVE-202

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
< 2.92rel2
Fixed
rhcos-aarch64-4.19.9.6.202607151909-0 as a component of Red Hat OpenShift Container Platform 4.19; rhcos-ppc64le-4.19.9.6.202607151909-0 as a component of Red Hat OpenShift Container Platform 4.19; rhcos-s390x-4.19.9.6.202607151909-0 as a component of Red Hat OpenShift Container Platform 4.19; rhcos-x86_64-4.19.9.6.202607151909-0 as a component of Red Hat OpenShift Container Platform 4.19; dnsmasq-0:2.90-7.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-0:2.90-7.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-0:2.90-7.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-0:2.90-7.el10_2.src as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-0:2.90-7.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-debuginfo-0:2.90-7.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-debuginfo-0:2.90-7.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-debuginfo-0:2.90-7.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-debuginfo-0:2.90-7.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-debugsource-0:2.90-7.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-debugsource-0:2.90-7.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-debugsource-0:2.90-7.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-debugsource-0:2.90-7.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-utils-0:2.90-7.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-utils-0:2.90-7.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-utils-0:2.90-7.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-utils-0:2.90-7.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-utils-debuginfo-0:2.90-7.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-utils-debuginfo-0:2.90-7.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-utils-debuginfo-0:2.90-7.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-utils-debuginfo-0:2.90-7.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); dnsmasq-0:2.79-36.el8_10.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8); dnsmasq-0:2.79-36.el8_10.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8); dnsmasq-0:2.79-36.el8_10.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8); dnsmasq-0:2.79-36.el8_10.src as a component of Red Hat Enterprise Linux AppStream (v. 8); dnsmasq-0:2.79-36.el8_10.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8); and 58 more
Action
For OpenShift Container Platform 4.19 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.19/html/release_notes/ You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags. The sha values for the release are as follows: (For x86_64 architecture) The image digest is sha256:8367df5ccbec71bfd55d827da81c659e301e17073b8a1a47e43d3e201adb4fd1 (For s390x architecture) The image digest is sha256:8eb5fa80e5e92443a0870c876e82b03971051c4285d9f71ef025eea098448dff (For ppc64le architecture) The image digest is sha256:5d7790ac52e357afe0a15363f4eefd505029cc49a3fc147787cc5b96d8bbc666 (For aarch64 architecture) The image digest is sha256:ed4761bb6a0bb26e5250aa36776dbe48d9ccab7fb1a05a253aa6ef2d59d32fde All OpenShift Container Platform 4.19 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshift_container_platform/4.19/html-single/updating_clusters/index#updating-cluster-cli.
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 11 May 2026 · Last source change 1 Sept 2026, 12:05 UTC · CWE-835 · Loop with Unreachable Exit Condition ('Infinite Loop')

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
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-2026-29152
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment

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

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2026-29152↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗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-2026-4890 · cve.blacktree.nl