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TI-2026-40970 Aliases CVE-2026-56817GHSA-4qhr-g3c6-fcfx

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

Priority MEDIUM 43CWE-611Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
—
Confidentiality · integrity · availability
High · None · Low
Fix status
Partial Red Hat: 2 fixed, 2 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat.

Summary

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 it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00694 53rd percentileScored 2026-11-07
Fix Partial netty (netty): 4.2.16.Final, 4.1.136.Finalio.netty:netty-codec-xml (Maven): 4.2.16.Final, 4.1.136.FinalRed Hat: 2 advisoriesRed Hat: 2 fixed, 2 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
nettynetty4.2.0.Final to before 4.2.16.Final; 4.1.0.Final to before 4.1.136.Final4.2.16.Final, 4.1.136.FinalPatch availableCNA
—io.netty:netty-codec-xml (Maven)4.2.0.Final to before 4.2.16.Final4.2.16.FinalPatch availableGHSA-4qhr-g3c6-fcfx
—io.netty:netty-codec-xml (Maven)4.1.0.Final to before 4.1.136.Final4.1.136.FinalPatch availableGHSA-4qhr-g3c6-fcfx
  • netty Vendornetty Affected 4.2.0.Final to before 4.2.16.Final; 4.1.0.Final to before 4.1.136.Final Fixed in 4.2.16.Final, 4.1.136.Final Patch available CNA
  • io.netty:netty-codec-xml (Maven) Vendor— Affected 4.2.0.Final to before 4.2.16.Final Fixed in 4.2.16.Final Patch available GHSA-4qhr-g3c6-fcfx
  • io.netty:netty-codec-xml (Maven) Vendor— Affected 4.1.0.Final to before 4.1.136.Final Fixed in 4.1.136.Final Patch available GHSA-4qhr-g3c6-fcfx

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*4.1.0 to before 4.1.136; 4.2.0 to before 4.2.16Vulnerablenetty
  • cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:* Versions 4.1.0 to before 4.1.136; 4.2.0 to before 4.2.16 Vulnerable ·netty

Remediation

  • Fix · CNA netty (netty) Fixed in 4.2.16.Final, 4.1.136.Final
  • Fix · GHSA-4qhr-g3c6-fcfx io.netty:netty-codec-xml (Maven) Fixed in 4.2.16.Final Advisory →
  • Fix · GHSA-4qhr-g3c6-fcfx io.netty:netty-codec-xml (Maven) Fixed in 4.1.136.Final Advisory →

Red Hat 2 advisories

  • RHSA-2026:69296 Released 2026-09-21 · Red Hat rating Important
    Red Hat Data Grid 8.6.3 security update
    • Red Hat Data Grid 8.6.3
  • RHSA-2026:54622 Released 2026-08-13 · Red Hat rating Important
    Red Hat Build of Apache Camel 4.18.3 for Spring Boot release.
    • Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat JBoss Enterprise Application Platform 7AffectedNo fix yet: Fix deferred
Red Hat Single Sign-On 7AffectedNo fix yet: Fix deferred
Red Hat Data Grid 8.6.3Fixed RHSA-2026:69296
Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16Fixed RHSA-2026:54622
Not affected: 1 product
  • Red Hat JBoss Enterprise Application Platform Expansion Pack

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-56817
  2. 2026-10-03 Alias added: GHSA-4qhr-g3c6-fcfx

References

Patch 2

Advisory 2

Other 3

  • TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
  • TI-2026-30861 Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization CVSS 3.1CRITICAL 9.8
  • TI-2026-30864 Netty: HttpClientCodec response desynchronization CVSS 3.1CRITICAL 9.1
  • TI-2026-30859 Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder) CVSS 3.1CRITICAL 9.1
  • TI-2026-40973 Netty: Missing CertificateID Validation in OCSP Response Allows Replay Attacks CVSS 3.1CRITICAL 9.1
  • TI-2026-40972 Uncontrolled resource consumption in netty CVSS 3.1HIGH 7.5
See all 92 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences