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Full vulnerability report · 2026
CVE-2020-37127High confidence

dnsmasq-utils 2.79-1 - 'dhcp_release' Denial of Service

dnsmasq · dnsmasq-utils

6.9MediumCVSS 4.0
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 20 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • EPSS is 0.21% for the current model date.

Compensating controls

  • Apply the linked authoritative mitigation while planning the permanent fix.
  • Restrict local access and enforce least privilege on affected hosts.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs dnsmasq dnsmasq-utils and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  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: As exposure requiresRemediation target: Within 365 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.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 20 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

4 package states
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.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcednsmasqVendor fix publishedDebian records a fixed source-package version for this release.2.80-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourcednsmasqVendor fix publishedDebian records a fixed source-package version for this release.2.80-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourcednsmasqVendor fix publishedDebian records a fixed source-package version for this release.2.80-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourcednsmasqVendor fix publishedDebian records a fixed source-package version for this release.2.80-1Debian Security Tracker ↗Source updated 5 Oct 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-2020-37127 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitydnsmasq: dnsmasq-utils 'dhcp_release' Denial of Service
20 known affected

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

  • dnsmasq as a component of Red Hat Enterprise Linux 10
  • dnsmasq-utils as a component of Red Hat Enterprise Linux 10
  • dnsmasq.src as a component of Red Hat Enterprise Linux 10
  • 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
  • dnsmasq as a component of Red Hat Enterprise Linux 8
  • dnsmasq-utils as a component of Red Hat Enterprise Linux 8
  • dnsmasq.src as a component of Red Hat Enterprise Linux 8
Summary
Dnsmasq-utils 2.79-1 contains a buffer overflow vulnerability in the dhcp_release utility that allows attackers to cause a denial of service by supplying excessive input. Attackers can trigger a core dump and terminate the dhcp_release process by sending a crafted input string longer than 16 characters.
Remediation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
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-2020-31023

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 actionPatch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 20 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

Dnsmasq-utils 2.79-1 contains a buffer overflow vulnerability in the dhcp_release utility that allows attackers to cause a denial of service by supplying excessive input. Attackers can trigger a core dump and terminate the dhcp_release process by sending a crafted input string longer than 16 characters.

What

Dnsmasq-utils 2.79-1 contains a buffer overflow vulnerability in the dhcp_release utility that allows attackers to cause a denial of service by supplying excessive input. Attackers can trigger a core dump and terminate the dhcp_release process by sending a crafted input string longer than 16 characters.

Why

A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

How

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

What

Dnsmasq-utils 2.79-1 contains a buffer overflow vulnerability in the dhcp_release utility that allows attackers to cause a denial of service by supplying excessive input. Attackers can trigger a core dump and terminate the dhcp_release process by sending a crafted input string longer than 16 characters.

Why

A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

How

An attacker operating through local access 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

CISA Vulnrichment records proof-of-concept exploitation in its SSVC data. BlackTree has not independently executed or validated exploit material.

Likely attack path
local access → Stack-based Buffer Overflow → disrupt the affected service
Attack surface
Local
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-121 ↗

CWE-121: Stack-based Buffer Overflow. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
UnauthenticatedDenial of serviceCWE-121Public exploit reference
A

Official authority intelligence

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

Cyber Security Agency of Singapore · English · CSA-SB-20260211Security Bulletin 11 Feb 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 11 Feb 2026, published on 11 February 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

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.
Fix availability varies by product
Affected
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
04

Evidence and provenance

Published 5 Feb 2026 · Last source change 5 Feb 2026, 21:18 UTC · CWE-121 · Stack-based Buffer Overflow

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-2020-31023
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD not scheduled

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
    dnsmasq as a component of Red Hat Enterprise Linux 10; dnsmasq-utils as a component of Red Hat Enterprise Linux 10; dnsmasq.src as a component of Red Hat Enterprise Linux 10; 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; dnsmasq as a component of Red Hat Enterprise Linux 8; dnsmasq-utils as a component of Red Hat Enterprise Linux 8; dnsmasq.src as a component of Red Hat Enterprise Linux 8; dnsmasq as a component of Red Hat Enterprise Linux 9; dnsmasq-utils as a component of Red Hat Enterprise Linux 9; dnsmasq.src as a component of Red Hat Enterprise Linux 9; openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4; openshift4/ose-baremetal-runtimecfg-rhel8 as a component of Red Hat OpenShift Container Platform 4; openshift4/ose-baremetal-runtimecfg-rhel9 as a component of Red Hat OpenShift Container Platform 4; rhoso-operators/infra-rhel9-operator as a component of Red Hat OpenStack Platform 18.0
    After
    dnsmasq as a component of Red Hat Enterprise Linux 10; dnsmasq-utils as a component of Red Hat Enterprise Linux 10; dnsmasq.src as a component of Red Hat Enterprise Linux 10; 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; dnsmasq as a component of Red Hat Enterprise Linux 8; dnsmasq-utils as a component of Red Hat Enterprise Linux 8; dnsmasq.src as a component of Red Hat Enterprise Linux 8; dnsmasq as a component of Red Hat Enterprise Linux 9; dnsmasq-utils as a component of Red Hat Enterprise Linux 9; dnsmasq.src as a component of Red Hat Enterprise Linux 9; openshift/ose-rhel-coreos-8 as a component of Red Hat OpenShift Container Platform 4; openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4; openshift4/ose-baremetal-runtimecfg-rhel8 as a component of Red Hat OpenShift Container Platform 4; openshift4/ose-baremetal-runtimecfg-rhel9 as a component of Red Hat OpenShift Container Platform 4; rhoso-operators/infra-rhel9-operator as a component of Red Hat OpenStack Platform 18.0
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2020-31023↗Vendor CSAF · Red Hat Product Security↗CISA Vulnrichment SSVC evidence↗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-2020-37127 · cve.blacktree.nl