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Full vulnerability report · 2026
CVE-2026-56817High confidence

Netty: XML External Entity (XXE) injection via unconfigured XML factory when DTD and entity processing are enabled

netty · netty

Official source article: GitHub GHSA-4QHR-G3C6-FCFX ↗. Check the applicable product and release in the original source.

8.3HighCVSS 4.0
Recommended action
Patch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 4 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 severityHighOperational priority:High, unchanged from published severity.unchanged

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 0.69% 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.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs netty netty 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 30 daysRemediation target: Within 180 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 4 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, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

5 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 4 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 releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcenettyAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · esm-appsnettyUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical 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 packageAffected rangeFirst fixed versionEvidence
Mavenio.netty:netty-codec-xmlECOSYSTEM: introduced 4.2.0.Final; fixed 4.2.16.Final4.2.16.FinalOSV record ↗aggregator derived · 10 Sep 2026
Mavenio.netty:netty-codec-xmlECOSYSTEM: introduced 4.1.0.Final; fixed 4.1.136.Final4.1.136.FinalOSV record ↗aggregator derived · 10 Sep 2026
mavenio.netty:netty-codec-xml>= 4.2.0.Final, <= 4.2.15.Final4.2.16.FinalGitHub advisory ↗upstream repository advisory · 22 Jul 2026
mavenio.netty:netty-codec-xml>= 4.1.0.Final, <= 4.1.135.Final4.1.136.FinalGitHub advisory ↗upstream repository advisory · 22 Jul 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-2026-56817 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityio.netty/netty-codec-xml: Netty: Information disclosure via XML External Entity (XXE) vulnerability
7 known affected

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

  • eap74-els-openjdk11-openshift-rhel8/eap74-els-openjdk11-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7
  • eap74-els-openjdk17-openshift-rhel8/eap74-els-openjdk17-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7
  • eap74-els-openjdk8-openshift-rhel8/eap74-els-openjdk8-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7
  • jboss-eap-7-eap74-els-openjdk17-openshift-rhel8/jboss-eap-7-eap74-els-openjdk17-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7
  • jboss-eap-7-eap74-els-openjdk8-openshift-rhel8/jboss-eap-7-eap74-els-openjdk8-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7
  • netty-codec-xml as a component of Red Hat JBoss Enterprise Application Platform 7
  • netty-codec-xml as a component of Red Hat Single Sign-On 7
Summary
A flaw was found in Netty, a network application framework. A remote attacker could exploit this vulnerability by sending specially crafted XML data containing a DOCTYPE declaration to a vulnerable XmlDecoder within the Netty channel pipeline. This can lead to an XML External Entity (XXE) vulnerability, potentially allowing the attacker to disclose sensitive information from the system.
Remediation
Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
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-2026-47579

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

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 4 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

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final, any caller that can deliver bytes to a Netty channel pipeline containing `XmlDecoder` can send XML with a `DOCTYPE` declaration to an `AsyncXMLInputFactory` instantiated with no security configuration, leaving DTD and entity handling active depending on Aalto XML async parser behavior and creating conditional XML external entity risk. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

What

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final, any caller that can deliver bytes to a Netty channel pipeline containing `XmlDecoder` can send XML with a `DOCTYPE` declaration to an `AsyncXMLInputFactory` instantiated with no security configuration, leaving DTD and entity handling active depending on Aalto XML async parser behavior and creating conditional XML external entity risk. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

Why

The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.

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

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final, any caller that can deliver bytes to a Netty channel pipeline containing `XmlDecoder` can send XML with a `DOCTYPE` declaration to an `AsyncXMLInputFactory` instantiated with no security configuration, leaving DTD and entity handling active depending on Aalto XML async parser behavior and creating conditional XML external entity risk. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

Why

The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.

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
?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 → Improper Restriction of XML External Entity Reference → 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
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-611 ↗

CWE-611: Improper Restriction of XML External Entity Reference. The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.

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

Common Vulnerability Scoring System 4.0: 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.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.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VALowVulnerable-system availability: A successful attack can cause a limited 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
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.
NetworkUnauthenticatedCWE-611
A

Official authority intelligence

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

BSI · German · WID-SEC-2026-2356Netty: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Netty ausnutzen, um Sicherheitsprüfungen zu umgehen, Anfragen oder Header zu manipulieren, Zertifikatsprüfungen zu unterlaufen sowie einen Denial of Service zu verursachen.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-026185NettyにおけるXML 外部エンティティの脆弱性

Nettyは、プロトコルサーバーおよびクライアントの開発のためのネットワークアプリケーションフレームワークです。バージョン4.2.0.Finalから4.2.15.Finalおよび4.1.0.Finalから4.1.135.Finalにおいて、Nettyチャネルパイプラインに`XmlDecoder`が含まれている場合、バイトを送信可能な任意の呼び出し元が、セキュリティ設定なしでインスタンス化された`AsyncXMLInputFactory`に`DOCTYPE`宣言を含むXMLを送信できます。その結果、DTDおよびエンティティ処理がAalto XML非同期パーサーの動作に依存して有効なままとなり、条件付きのXML外部エンティティリスクが発生します。この問題はバージョン4.1.136.Finalおよび4.2.16.Final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.
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. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
Official vendor articles2 stored documents

Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.

  • Release netty-4.1.136.Final · netty/netty · GitHub →Original publisher ↗Searchable text snapshot · Captured 27 Sep 2026netty / netty Public Uh oh! There was an error while loading. Please reload this page . Notifications You must be signed in to change notification settings Fork 16.3k Star 35.1k Code Issues 627 Pull requests 103 Discussions Actions Projects Wiki Security and quality 117 Insights Additional navigation
  • Release netty-4.2.16.Final · netty/netty · GitHub →Original publisher ↗Searchable text snapshot · Captured 27 Sep 2026netty / netty Public Uh oh! There was an error while loading. Please reload this page . Notifications You must be signed in to change notification settings Fork 16.3k Star 35.1k Code Issues 627 Pull requests 103 Discussions Actions Projects Wiki Security and quality 117 Insights Additional navigation
04

Evidence and provenance

Published 21 Jul 2026 · Last source change 22 Jul 2026, 15:42 UTC · CWE-611 · Improper Restriction of XML External Entity Reference

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-2026-47579
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
    netty-codec-xml as a component of Red Hat Data Grid 8; eap74-els-openjdk11-openshift-rhel8/eap74-els-openjdk11-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7; eap74-els-openjdk17-openshift-rhel8/eap74-els-openjdk17-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7; eap74-els-openjdk8-openshift-rhel8/eap74-els-openjdk8-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7; jboss-eap-7-eap74-els-openjdk17-openshift-rhel8/jboss-eap-7-eap74-els-openjdk17-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7; jboss-eap-7-eap74-els-openjdk8-openshift-rhel8/jboss-eap-7-eap74-els-openjdk8-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7; netty-codec-xml as a component of Red Hat JBoss Enterprise Application Platform 7; netty-codec-xml as a component of Red Hat Single Sign-On 7 · Fixed: Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16
    After
    eap74-els-openjdk11-openshift-rhel8/eap74-els-openjdk11-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7; eap74-els-openjdk17-openshift-rhel8/eap74-els-openjdk17-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7; eap74-els-openjdk8-openshift-rhel8/eap74-els-openjdk8-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7; jboss-eap-7-eap74-els-openjdk17-openshift-rhel8/jboss-eap-7-eap74-els-openjdk17-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7; jboss-eap-7-eap74-els-openjdk8-openshift-rhel8/jboss-eap-7-eap74-els-openjdk8-openshift-rhel8 as a component of Red Hat JBoss Enterprise Application Platform 7; netty-codec-xml as a component of Red Hat JBoss Enterprise Application Platform 7; netty-codec-xml as a component of Red Hat Single Sign-On 7 · Fixed: Red Hat Data Grid 8.6.3; Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16
    Red Hat Product Security ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    >= 4.2.0.Final, < 4.2.16.Final; >= 4.1.0.Final, < 4.1.136.Final · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    >= 4.2.0.Final, < 4.2.16.Final; >= 4.1.0.Final, < 4.1.136.Final · Fixed: Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
    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
Fixed release recorded from official guidance
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2026-47579↗Red Hat Product Security security advisory↗CVE authority or vendor reference · GitHub GHSA-4QHR-G3C6-FCFX↗Patch or update reference↗Patch or update 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-2026-56817 · cve.blacktree.nl