High 8.3Published Jul 21, 2026

CVE-2026-56817Netty: XML External Entity (XXE) injection via unconfigured XML factory when DTD and entity processing are enabled

Updated under an hour ago (Oct 28, 2026, 1:50 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 8.3 HIGH (v4.0, CNA)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
Weakness (CWE): CWE-611
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jul 22, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

netty netty netty:netty (from the name)	from 4.2.0.Final, < 4.2.16.Final; from 4.1.0.Final, < 4.1.136.Final	CNA record
netty netty netty:netty	from 4.1.0 before 4.1.136; from 4.2.0 before 4.2.16	NVD

References

References

https://github.com/netty/netty/security/advisories/GHSA-4qhr-g3c6-fcfx	x-refsource-confirm, vendor-advisory
https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b	x-refsource-misc, patch
https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6	x-refsource-misc, patch
https://github.com/netty/netty/releases/tag/netty-4.1.136.Final	x-refsource-misc, release-notes
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.