GHSA-CJX3-73HR-RPW7
Vulnerability from github – Published: 2026-09-24 19:35 – Updated: 2026-09-24 19:35http4s-scala-xml provides EntityDecoder[F, scala.xml.Elem] instances that parse XML message bodies. These decoders used a javax.xml.parsers.SAXParserFactory obtained from SAXParserFactory.newInstance without any security configuration. With the JDK's default settings, the parser resolves DOCTYPE declarations, external general and parameter entities, and external DTDs.
An application that uses these decoders to parse untrusted XML is vulnerable to XML External Entity (XXE) attacks. An attacker can craft a request that:
- discloses local files readable by the service process,
- performs server-side request forgery (SSRF) against internal network resources, and/or
- causes denial of service through entity expansion.
Impact
Any service that derives an XML EntityDecoder from this library and parses attacker-controlled input is affected.
Patches
The default SAXParserFactory is now hardened:
- secure processing is enabled
- DOCTYPE declarations are disallowed
- external general/parameter entities and external DTD loading are disabled
- DTD URIs are not resolved
- XInclude is disabled.
These defaults match scala.xml.XMLLoader's defaults since 2.0.0.
Workarounds
Before upgrading, override ElemInstances#saxFactory with a hardened factory.
val secured = new ElemInstances {
override protected val saxFactory = {
val f = javax.xml.parsers.SAXParserFactory.newInstance
f.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true)
// etc.
f
}
}
import secured._
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.24.0"
},
"package": {
"ecosystem": "Maven",
"name": "org.http4s:http4s-scala-xml_2.12"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.24.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.24.0"
},
"package": {
"ecosystem": "Maven",
"name": "org.http4s:http4s-scala-xml_2.13"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.24.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.0.0-M38.1"
},
"package": {
"ecosystem": "Maven",
"name": "org.http4s:http4s-scala-xml_2.13"
},
"ranges": [
{
"events": [
{
"introduced": "1.0.0-M1"
},
{
"fixed": "1.0.0-M39"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.24.0"
},
"package": {
"ecosystem": "Maven",
"name": "org.http4s:http4s-scala-xml_3"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.24.1"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.0.0-M38.1"
},
"package": {
"ecosystem": "Maven",
"name": "org.http4s:http4s-scala-xml_3"
},
"ranges": [
{
"events": [
{
"introduced": "1.0.0-M1"
},
{
"fixed": "1.0.0-M39"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-61741"
],
"database_specific": {
"cwe_ids": [
"CWE-611"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-24T19:35:16Z",
"nvd_published_at": "2026-09-24T18:17:16Z",
"severity": "CRITICAL"
},
"details": "http4s-scala-xml provides `EntityDecoder[F, scala.xml.Elem]` instances that parse XML message bodies. These decoders used a `javax.xml.parsers.SAXParserFactory` obtained from `SAXParserFactory.newInstance` without any security configuration. With the JDK\u0027s default settings, the parser resolves DOCTYPE declarations, external general and parameter entities, and external DTDs.\n\nAn application that uses these decoders to parse untrusted XML is vulnerable to XML External Entity (XXE) attacks. An attacker can craft a request that:\n\n- discloses local files readable by the service process,\n- performs server-side request forgery (SSRF) against internal network resources, and/or\n- causes denial of service through entity expansion.\n\n### Impact\n\nAny service that derives an XML `EntityDecoder` from this library and parses attacker-controlled input is affected.\n\n### Patches\n\nThe default SAXParserFactory is now hardened: \n- secure processing is enabled\n- `DOCTYPE` declarations are disallowed\n- external general/parameter entities and external DTD loading are disabled\n- DTD URIs are not resolved\n- XInclude is disabled.\n\nThese defaults match `scala.xml.XMLLoader`\u0027s defaults since 2.0.0.\n\n### Workarounds\n\nBefore upgrading, override `ElemInstances#saxFactory` with a hardened factory.\n\n```scala\n val secured = new ElemInstances {\n override protected val saxFactory = {\n val f = javax.xml.parsers.SAXParserFactory.newInstance\n f.setFeature(\"http://apache.org/xml/features/disallow-doctype-decl\", true)\n // etc.\n f\n }\n }\n import secured._\n```",
"id": "GHSA-cjx3-73hr-rpw7",
"modified": "2026-09-24T19:35:16Z",
"published": "2026-09-24T19:35:16Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/http4s/http4s-scala-xml/security/advisories/GHSA-cjx3-73hr-rpw7"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-61741"
},
{
"type": "WEB",
"url": "https://github.com/http4s/http4s-scala-xml/commit/326f965a2c45fc2ddbc22545dcf551b0f719f4c8"
},
{
"type": "PACKAGE",
"url": "https://github.com/http4s/http4s-scala-xml"
},
{
"type": "WEB",
"url": "https://github.com/http4s/http4s-scala-xml/releases/tag/v0.24.1"
},
{
"type": "WEB",
"url": "https://github.com/http4s/http4s-scala-xml/releases/tag/v1.0.0-M39"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L",
"type": "CVSS_V3"
}
],
"summary": "http4s-scala-xml has an XML External Entity (XXE) processing issue"
}
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