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CVE-2026-56817Netty: XML External Entity (XXE) injection via unconfigured XML factory when DTD and entity processing are enabled
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.
8.3 HIGHEPSS 0.69%Not in KEVNVD: Analyzed
Overview
Severity
| Score | Severity | Version | Vector String |
|---|---|---|---|
| 8.3 | HIGH | 4.0GitHub_M (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 |
| 9.8 | CRITICAL | 3.1NVD | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
Details
- CVE ID
- CVE-2026-56817
- Status
- Analyzed
- Assigner (CNA)
- GitHub_M
- Published
- Jul 21, 2026
- Last modified
- 2026-07-30 14:48 UTC
- Weaknesses
- CWE-611 · Improper Restriction of XML External Entity Reference
Affected Products
As published by the CNA in the CVE record.
nettynetty2 version ranges
- >= 4.2.0.Final, < 4.2.16.Final
- >= 4.1.0.Final, < 4.1.136.Final
References
- github.com https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b
- github.com https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6
- github.com https://github.com/netty/netty/releases/tag/netty-4.1.136.Final
- github.com https://github.com/netty/netty/releases/tag/netty-4.2.16.Final
- github.com https://github.com/netty/netty/security/advisories/GHSA-4qhr-g3c6-fcfx