Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.65% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-24281High confidence
Apache ZooKeeper: Reverse-DNS fallback enables hostname verification bypass in ZooKeeper ZKTrustManager
Apache Software Foundation · Apache ZooKeeper
7.4HighCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productHigh technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 2 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Apache Software Foundation Apache ZooKeeper and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 2 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Debian Security Tracker: 2 affected package states with no published fix
Distribution package intelligence
5 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
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 2 affected package states 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 release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | zookeeper | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian bookwormbookworm · source | zookeeper | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian forkyforky · source | zookeeper | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.9.5-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian sidsid · source | zookeeper | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.9.5-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | zookeeper | Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
Open-source package ranges4 source-attributed ranges
These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.
| Ecosystem and package | Affected range | First fixed version | Evidence |
|---|---|---|---|
| Mavenorg.apache.zookeeper:zookeeper | ECOSYSTEM: introduced 3.8.0; fixed 3.8.6 | 3.8.6 | OSV record ↗aggregator derived · 10 Sep 2026 |
| Mavenorg.apache.zookeeper:zookeeper | ECOSYSTEM: introduced 3.9.0; fixed 3.9.5 | 3.9.5 | OSV record ↗aggregator derived · 10 Sep 2026 |
| mavenorg.apache.zookeeper:zookeeper | >= 3.8.0, < 3.8.6 | 3.8.6 | GitHub advisory ↗github reviewed aggregator · 10 Mar 2026 |
| mavenorg.apache.zookeeper:zookeeper | >= 3.9.0, < 3.9.5 | 3.9.5 | GitHub advisory ↗github reviewed aggregator · 10 Mar 2026 |
Direct vendor intelligence
1 currentAuthoritative 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.
CVE-2026-24281 · CSAF 2.0 · revision 3 · finalRed Hat Product SecurityApache ZooKeeper: Apache ZooKeeper: Impersonation of servers or clients via reverse DNS spoofing
The vendor explicitly identifies these products as affected by this CVE.
- zookeeper as a component of Red Hat build of Debezium 2
- zookeeper as a component of Red Hat build of Debezium 3
- zookeeper as a component of Red Hat Fuse 7
- zookeeper as a component of Red Hat JBoss Enterprise Application Platform Expansion Pack
- offline-knowledge-portal/rhokp-rhel9 as a component of Red Hat Offline Knowledge Portal
- rhoai/odh-modelmesh-rhel8 as a component of Red Hat OpenShift AI (RHOAI)
- zookeeper as a component of streams for Apache Kafka 3
- Summary
- A flaw was found in Apache ZooKeeper. The ZKTrustManager component's hostname verification process can fall back to reverse DNS (PTR) lookup when IP Subject Alternative Name (SAN) validation fails. This vulnerability allows an attacker who can control or spoof PTR records to impersonate ZooKeeper servers or clients, provided they possess a valid certificate for the PTR name. This could lead to unauthorized access or manipulation of ZooKeeper services.
- Remediation
- Before applying the update, back up your existing installation, including all applications, configuration files, databases and database settings. The References section of this erratum contains a download link (you must log in to download the update).
High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 2 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.
What
Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.
Why
The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.
How
An attacker operating through a network path 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
Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.
Why
The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.
How
An attacker operating through a network path 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 No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 → Reliance on Reverse DNS Resolution for a Security-Critical Action → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- High: exploitation depends on specific conditions
- 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-350 ↗
CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action. The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.
- 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:H/PR:N/UI:N/S:U/C:H/I:H/A:NCommon 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.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.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.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.ANoneAvailability impact: No direct loss is represented by this metric.- 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.
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
- zookeeper as a component of Red Hat build of Debezium 2
- zookeeper as a component of Red Hat build of Debezium 3
- zookeeper as a component of Red Hat Fuse 7
- zookeeper as a component of Red Hat JBoss Enterprise Application Platform Expansion Pack
- offline-knowledge-portal/rhokp-rhel9 as a component of Red Hat Offline Knowledge Portal
- rhoai/odh-modelmesh-rhel8 as a component of Red Hat OpenShift AI (RHOAI)
- zookeeper as a component of streams for Apache Kafka 3
- Fixed
- Red Hat AMQ Broker 7.12.7
- org.apache.zookeeper.zookeeper-3.8.4.redhat-00018.jar as a component of Red Hat JBoss Enterprise Application Platform 6.0.7.GA
- registry.redhat.io/rhoai/odh-modelmesh-rhel9@sha256:ef9eae46fb64606e5d943c1dbc30eddbad35e50a2e67062f4c1a98bea48da038_amd64 as a component of Red Hat OpenShift AI 2.25
- registry.redhat.io/rhoai/odh-modelmesh-rhel9@sha256:f3a60cbfd7a3674fcacb56f9a7cfe6e10c6d24a690d107cb5b258986e154f3d3_arm64 as a component of Red Hat OpenShift AI 2.25
- Streams for Apache Kafka 2.9.4
- 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. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 7 Mar 2026 · Last source change 15 Jul 2026, 01:17 UTC · CWE-350 · Reliance on Reverse DNS Resolution for a Security-Critical Action
CVE recordCVE.org · 5.2
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-10139
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- zookeeper as a component of Red Hat build of Debezium 2; zookeeper as a component of Red Hat build of Debezium 3; zookeeper as a component of Red Hat Fuse 7; zookeeper as a component of Red Hat JBoss Enterprise Application Platform Expansion Pack; offline-knowledge-portal/rhokp-rhel9 as a component of Red Hat Offline Knowledge Portal; rhoai/odh-modelmesh-rhel8 as a component of Red Hat OpenShift AI (RHOAI); zookeeper as a component of streams for Apache Kafka 3 · Fixed: Red Hat AMQ Broker 7.12.7; Red Hat AMQ Broker 7.13.5; Red Hat AMQ Broker 7.14.0; org.apache.zookeeper.zookeeper-3.8.4.redhat-00018.jar as a component of Red Hat JBoss Enterprise Application Platform 6.0.7.GA; registry.redhat.io/rhoai/odh-modelmesh-rhel9@sha256:ef9eae46fb64606e5d943c1dbc30eddbad35e50a2e67062f4c1a98bea48da038_amd64 as a component of Red Hat OpenShift AI 2.25; registry.redhat.io/rhoai/odh-modelmesh-rhel9@sha256:f3a60cbfd7a3674fcacb56f9a7cfe6e10c6d24a690d107cb5b258986e154f3d3_arm64 as a component of Red Hat OpenShift AI 2.25; Streams for Apache Kafka 2.9.4
- After
- zookeeper as a component of Red Hat build of Debezium 2; zookeeper as a component of Red Hat build of Debezium 3; zookeeper as a component of Red Hat Fuse 7; zookeeper as a component of Red Hat JBoss Enterprise Application Platform Expansion Pack; offline-knowledge-portal/rhokp-rhel9 as a component of Red Hat Offline Knowledge Portal; rhoai/odh-modelmesh-rhel8 as a component of Red Hat OpenShift AI (RHOAI); zookeeper as a component of streams for Apache Kafka 3 · Fixed: Red Hat AMQ Broker 7.12.7; org.apache.zookeeper.zookeeper-3.8.4.redhat-00018.jar as a component of Red Hat JBoss Enterprise Application Platform 6.0.7.GA; registry.redhat.io/rhoai/odh-modelmesh-rhel9@sha256:ef9eae46fb64606e5d943c1dbc30eddbad35e50a2e67062f4c1a98bea48da038_amd64 as a component of Red Hat OpenShift AI 2.25; registry.redhat.io/rhoai/odh-modelmesh-rhel9@sha256:f3a60cbfd7a3674fcacb56f9a7cfe6e10c6d24a690d107cb5b258986e154f3d3_arm64 as a component of Red Hat OpenShift AI 2.25; Streams for Apache Kafka 2.9.4
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- 3.9.0 ≤ 3.9.4; 3.8.0 ≤ 3.8.5 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- 3.9.0 ≤ 3.9.4; 3.8.0 ≤ 3.8.5 · Fixed: Before applying the update, back up your existing installation, including all applications, configuration files, databases and database settings. The References section of this erratum contains a download link (you must log in to download the update).
- Remediation statusRemediation status changed from Awaiting fix to Patch available.Red Hat Product Security ↗
- Before
- Awaiting fix
- After
- Patch available
CVE published
Fixed release recorded from official guidance
Fixed release recorded from official guidance
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.