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Full vulnerability report · 2026
CVE-2026-42960High confidence

Possible cache poisoning via promiscuous records for the authority section

NLnet Labs · Unbound

5.7MediumCVSS 4.0
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 1 structured product or package state 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.
  • EPSS is 0.27% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs NLnet Labs Unbound 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: 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 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

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

7 package states
Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 1 affected package state shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

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
Alpine v3.23v3.23 · mainunboundVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.1.25.2-r0Alpine Security Database ↗Source updated 6 Oct 2026
Alpine v3.22v3.22 · mainunboundVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.1.25.2-r0Alpine Security Database ↗Source updated 6 Oct 2026
Debian trixietrixie · sourceunboundVendor fix publishedDebian records a fixed source-package version for this release.1.22.0-2+deb13u3Debian Security Tracker ↗Source updated 7 Oct 2026
Debian bookwormbookworm · sourceunboundAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 7 Oct 2026
Debian forkyforky · sourceunboundVendor fix publishedDebian records a fixed source-package version for this release.1.25.1-1Debian Security Tracker ↗Source updated 7 Oct 2026
Debian sidsid · sourceunboundVendor fix publishedDebian records a fixed source-package version for this release.1.25.1-1Debian Security Tracker ↗Source updated 7 Oct 2026
Ubuntu 24.04 LTSnoble · standard archiveunboundVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.1.19.2-1ubuntu3.8Canonical Ubuntu Security ↗Source updated 6 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-2026-42960 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityunbound: Unbound DNS Cache Poisoning via Promiscuous Additional Section RRSet Acceptance
31 known affected

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

  • python3-unbound as a component of Red Hat Enterprise Linux 10
  • unbound as a component of Red Hat Enterprise Linux 10
  • unbound-anchor as a component of Red Hat Enterprise Linux 10
  • unbound-devel as a component of Red Hat Enterprise Linux 10
  • unbound-dracut as a component of Red Hat Enterprise Linux 10
  • unbound-libs as a component of Red Hat Enterprise Linux 10
  • unbound-utils as a component of Red Hat Enterprise Linux 10
  • unbound.src as a component of Red Hat Enterprise Linux 10
  • unbound as a component of Red Hat Enterprise Linux 6
  • unbound-devel as a component of Red Hat Enterprise Linux 6
  • unbound-libs as a component of Red Hat Enterprise Linux 6
  • unbound-python as a component of Red Hat Enterprise Linux 6
Summary
A flaw was found in Unbound's handling of DNS reply messages, complementing the earlier CVE-2025-11411 fix. Unbound accepts and caches address records from the additional section of DNS replies when they accompany authority section RRSets other than NS (such as MX records). A malicious actor who can inject crafted DNS responses—via packet spoofing or fragmentation attacks—can exploit this to poison Unbound's cache with attacker-controlled address records, potentially redirecting DNS resolution for affected domains.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
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-2026-31083

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 no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or fragmentation attacks. Unbound would then accept the relative address records in the additional section and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the additional section if they are not explicitly relevant only to authority NS records, mitigating the possible poison effect. This is a complement fix to CVE-2025-11411.

What

NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or fragmentation attacks. Unbound would then accept the relative address records in the additional section and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the additional section if they are not explicitly relevant only to authority NS records, mitigating the possible poison effect. This is a complement fix to CVE-2025-11411.

Why

The product, when processing trusted data, accepts any untrusted data that is also included with the trusted data, treating the untrusted data as if it were trusted.

How

An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to poisoning via promiscuous records for the authority section. Promiscuous RRSets that complement DNS replies in the authority section can be used to trick Unbound to cache such records. If an adversary is able to attach such records in a reply (i.e., spoofed packet, fragmentation attack) he would be able to poison Unbound's cache. A malicious actor can exploit the possible poisonous effect by injecting RRSets other than NS that are also accompanied by address records in a reply, for example MX. This could be achieved by trying to spoof a reply packet or fragmentation attacks. Unbound would then accept the relative address records in the additional section and cache them if the authority RRSet has enough trust at this point, i.e., in-zone data for the delegation point. Unbound 1.25.1 contains a patch with a fix that disregards address records from the additional section if they are not explicitly relevant only to authority NS records, mitigating the possible poison effect. This is a complement fix to CVE-2025-11411.

Why

The product, when processing trusted data, accepts any untrusted data that is also included with the trusted data, treating the untrusted data as if it were trusted.

How

An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

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
an adjacent network → Acceptance of Extraneous Untrusted Data With Trusted Data → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Adjacent
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-349 ↗

CWE-349: Acceptance of Extraneous Untrusted Data With Trusted Data. The product, when processing trusted data, accepts any untrusted data that is also included with the trusted data, treating the untrusted data as if it were trusted.

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

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

AVAdjacentAttack vector: The attacker must be on an adjacent or logically close network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATPresentAttack requirements: A particular deployment or execution condition must be present.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.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SIHighSubsequent-system integrity: A successful attack can cause a major loss.SAHighSubsequent-system availability: 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.
UnauthenticatedCWE-349
A

Official authority intelligence

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

BSI · German · WID-SEC-2026-2455Oracle Solaris Drittanbieterkomponenten: Mehrere Schwachstellen

Ein entfernter, anonymer oder authentisierter Angreifer kann mehrere Schwachstellen in verschiedenen Komponenten von Drittanbietern in Oracle Solaris ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.

Official advisory ↗
BSI · German · WID-SEC-2026-1599Unbound: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Unbound ausnutzen, um einen Denial of Service Zustand herbeizuführen, um möglicherweise Code auszuführen und um nicht näher spezifizierte Auswirkungen zu verursachen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260527Security Bulletin 27 May 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 27 May 2026, published on 27 May 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-016792NLnet Labsのunboundにおける信頼できるデータ受け入れ時の信頼できない無関係なデータの受け入れに関する脆弱性

NLnet LabsのUnboundはバージョン1.25.0まで（含む）において、権威セクションのプロミスキャス（曖昧）レコードを介したポイズニングの脆弱性があります。権威セクションのDNS応答を補完するプロミスキャスなRRSetは、Unboundを騙してこれらのレコードをキャッシュさせるために利用される可能性があります。攻撃者がそのようなレコードを応答に添付できる場合（例：偽装パケットや断片化攻撃）、Unboundのキャッシュを汚染することが可能です。悪意ある攻撃者はNSレコード以外に、例えばMXレコードのようなアドレスレコードを伴うRRSetを注入してこのポイズン効果を悪用できます。これは応答パケットの偽装や断片化攻撃によって達成される可能性があります。Unboundはその後、権威RRSetが十分な信頼を持つ場合に追加セクションの関連アドレスレコードを受け入れてキャッシュします。Unbound 1.25.1では、権威NSレコードに明示的に関連しない追加セクションのアドレスレコードを無視する修正が含まれており、このポイズン効果を緩和しています。これにより安全性が改善されました。

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
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
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 20 May 2026 · Last source change 20 May 2026, 13:04 UTC · CWE-349 · Acceptance of Extraneous Untrusted Data With Trusted Data

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-2026-31083
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
    < 1.25.1 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    < 1.25.1 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
    Red Hat Product Security ↗
  2. Remediation statusRemediation status changed from Mitigation available to Patch available.
    Before
    Mitigation available
    After
    Patch available
    Red Hat Product Security ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    python3-unbound as a component of Red Hat Enterprise Linux 10; unbound as a component of Red Hat Enterprise Linux 10; unbound-anchor as a component of Red Hat Enterprise Linux 10; unbound-devel as a component of Red Hat Enterprise Linux 10; unbound-dracut as a component of Red Hat Enterprise Linux 10; unbound-libs as a component of Red Hat Enterprise Linux 10; unbound-utils as a component of Red Hat Enterprise Linux 10; unbound.src as a component of Red Hat Enterprise Linux 10; unbound as a component of Red Hat Enterprise Linux 6; unbound-devel as a component of Red Hat Enterprise Linux 6; unbound-libs as a component of Red Hat Enterprise Linux 6; unbound-python as a component of Red Hat Enterprise Linux 6; unbound.src as a component of Red Hat Enterprise Linux 6; unbound as a component of Red Hat Enterprise Linux 7; unbound-devel as a component of Red Hat Enterprise Linux 7; unbound-libs as a component of Red Hat Enterprise Linux 7; unbound-python as a component of Red Hat Enterprise Linux 7; unbound.src as a component of Red Hat Enterprise Linux 7; python3-unbound as a component of Red Hat Enterprise Linux 8; unbound as a component of Red Hat Enterprise Linux 8; unbound-devel as a component of Red Hat Enterprise Linux 8; unbound-libs as a component of Red Hat Enterprise Linux 8; unbound.src as a component of Red Hat Enterprise Linux 8; python3-unbound as a component of Red Hat Enterprise Linux 9; unbound as a component of Red Hat Enterprise Linux 9; unbound-devel as a component of Red Hat Enterprise Linux 9; unbound-dracut as a component of Red Hat Enterprise Linux 9; unbound-libs as a component of Red Hat Enterprise Linux 9; unbound.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 · Fixed: unbound-main@aarch64 as a component of Red Hat Hardened Images; unbound-main@noarch as a component of Red Hat Hardened Images; unbound-main@src as a component of Red Hat Hardened Images; unbound-main@x86_64 as a component of Red Hat Hardened Images
    After
    python3-unbound as a component of Red Hat Enterprise Linux 10; unbound as a component of Red Hat Enterprise Linux 10; unbound-anchor as a component of Red Hat Enterprise Linux 10; unbound-devel as a component of Red Hat Enterprise Linux 10; unbound-dracut as a component of Red Hat Enterprise Linux 10; unbound-libs as a component of Red Hat Enterprise Linux 10; unbound-utils as a component of Red Hat Enterprise Linux 10; unbound.src as a component of Red Hat Enterprise Linux 10; unbound as a component of Red Hat Enterprise Linux 6; unbound-devel as a component of Red Hat Enterprise Linux 6; unbound-libs as a component of Red Hat Enterprise Linux 6; unbound-python as a component of Red Hat Enterprise Linux 6; unbound.src as a component of Red Hat Enterprise Linux 6; unbound as a component of Red Hat Enterprise Linux 7; unbound-devel as a component of Red Hat Enterprise Linux 7; unbound-libs as a component of Red Hat Enterprise Linux 7; unbound-python as a component of Red Hat Enterprise Linux 7; unbound.src as a component of Red Hat Enterprise Linux 7; python3-unbound as a component of Red Hat Enterprise Linux 8; unbound as a component of Red Hat Enterprise Linux 8; unbound-devel as a component of Red Hat Enterprise Linux 8; unbound-libs as a component of Red Hat Enterprise Linux 8; unbound.src as a component of Red Hat Enterprise Linux 8; python3-unbound as a component of Red Hat Enterprise Linux 9; unbound as a component of Red Hat Enterprise Linux 9; unbound-devel as a component of Red Hat Enterprise Linux 9; unbound-dracut as a component of Red Hat Enterprise Linux 9; unbound-libs as a component of Red Hat Enterprise Linux 9; unbound.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; and 1 more · Fixed: unbound-main@aarch64 as a component of Red Hat Hardened Images; unbound-main@noarch as a component of Red Hat Hardened Images; unbound-main@src as a component of Red Hat Hardened Images; unbound-main@x86_64 as a component of Red Hat Hardened Images
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Mitigation reference recorded
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2026-31083↗Red Hat Product Security security advisory↗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-2026-42960 · cve.blacktree.nl