CVE-2026-56817 (GCVE-0-2026-56817)

Vulnerability from cvelistv5 – Published: 2026-07-21 22:06 – Updated: 2026-07-21 22:06
VLAI
Title
Netty: XML External Entity (XXE) injection via unconfigured XML factory when DTD and entity processing are enabled
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.
Severity
8.3 (High)
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
CWE
  • CWE-611 - Improper Restriction of XML External Entity Reference
Assigner
References
Impacted products
Vendor Product Version
netty netty Affected: >= 4.2.0.Final, < 4.2.16.Final
Affected: >= 4.1.0.Final, < 4.1.136.Final
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "netty",
          "vendor": "netty",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.2.0.Final, \u003c 4.2.16.Final"
            },
            {
              "status": "affected",
              "version": "\u003e= 4.1.0.Final, \u003c 4.1.136.Final"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 8.3,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-611",
              "description": "CWE-611: Improper Restriction of XML External Entity Reference",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-21T22:06:56.481Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/netty/netty/security/advisories/GHSA-4qhr-g3c6-fcfx",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/netty/netty/security/advisories/GHSA-4qhr-g3c6-fcfx"
        },
        {
          "name": "https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b"
        },
        {
          "name": "https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6"
        },
        {
          "name": "https://github.com/netty/netty/releases/tag/netty-4.1.136.Final",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/netty/netty/releases/tag/netty-4.1.136.Final"
        },
        {
          "name": "https://github.com/netty/netty/releases/tag/netty-4.2.16.Final",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/netty/netty/releases/tag/netty-4.2.16.Final"
        }
      ],
      "source": {
        "advisory": "GHSA-4qhr-g3c6-fcfx",
        "discovery": "UNKNOWN"
      },
      "title": "Netty: XML External Entity (XXE) injection via unconfigured XML factory when DTD and entity processing are enabled"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-56817",
    "datePublished": "2026-07-21T22:06:56.481Z",
    "dateReserved": "2026-06-23T14:55:09.116Z",
    "dateUpdated": "2026-07-21T22:06:56.481Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}



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