CVE-2026-47079 (GCVE-0-2026-47079)
Vulnerability from cvelistv5 – Published: 2026-08-21 09:52 – Updated: 2026-08-21 12:19
VLAI
EPSS
VEX
Title
Round-trip Corruption via Improper Entity Escaping in xml_builder
Summary
Inappropriate Encoding for Output Context vulnerability in joshnuss xml_builder (XmlBuilder module) allows Content Spoofing, Cross-site Scripting.
This vulnerability is associated with program files lib/xml_builder.ex and program routines XmlBuilder.generate/1, XmlBuilder.generate/2, XmlBuilder.escape_string/1, XmlBuilder.escape_entity/1.
XmlBuilder.generate/1 does not escape literal & characters in text or attribute values when they are followed by an entity-like token (lt;, gt;, amp;, quot;, apos;). As a result, attacker-supplied input such as <script> is emitted verbatim into the serialized XML rather than being escaped to <script>. When a downstream XML parser later reads the document, it decodes the entity sequences into the literal characters <script>, promoting inert-looking text into real markup. This allows an attacker to bypass upstream filters that block raw < and > characters, injecting markup into any downstream consumer that parses the produced XML and renders the text content in a markup-sensitive context (HTML, SVG, RSS/Atom feeds). Both element text and attribute values are affected.
This issue affects xml_builder: from 0.0.6 before 2.4.1.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-21 12:17 UTC
CWE
- CWE-838 - Inappropriate Encoding for Output Context
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/joshnuss/xml_builder/security/… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-47079.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-47079 | related |
| https://github.com/joshnuss/xml_builder/commit/c3… | patch |
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| joshnuss | xml_builder |
Affected:
0.0.6 , < 2.4.1
(semver)
cpe:2.3:a:joshnuss:xml_builder:*:*:*:*:*:*:*:* |
|
| joshnuss | xml_builder |
Affected:
aae31e6e8ac837bcbb8afb816c0d14324b5cfe2b , < c3390e2046ec297b3bb8c30d5779cdfd6508c275
(git)
cpe:2.3:a:joshnuss:xml_builder:*:*:*:*:*:*:*:* |
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"vendor": "joshnuss",
"versions": [
{
"lessThan": "2.4.1",
"status": "affected",
"version": "0.0.6",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:joshnuss:xml_builder:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.XmlBuilder\u0027"
],
"packageName": "joshnuss/xml_builder",
"packageURL": "pkg:github/joshnuss/xml_builder",
"product": "xml_builder",
"programFiles": [
"lib/xml_builder.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.XmlBuilder\u0027:generate/1"
},
{
"name": "\u0027Elixir.XmlBuilder\u0027:generate/2"
},
{
"name": "\u0027Elixir.XmlBuilder\u0027:escape_string/1"
},
{
"name": "\u0027Elixir.XmlBuilder\u0027:escape_entity/1"
}
],
"repo": "https://github.com/joshnuss/xml_builder",
"vendor": "joshnuss",
"versions": [
{
"lessThan": "c3390e2046ec297b3bb8c30d5779cdfd6508c275",
"status": "affected",
"version": "aae31e6e8ac837bcbb8afb816c0d14324b5cfe2b",
"versionType": "git"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:joshnuss:xml_builder:*:*:*:*:*:*:*:*",
"versionEndExcluding": "2.4.1",
"versionStartIncluding": "0.0.6",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "AND"
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Peter Ullrich"
},
{
"lang": "en",
"type": "remediation developer",
"value": "Joshua Nussbaum"
},
{
"lang": "en",
"type": "coordinator",
"value": "Jonatan M\u00e4nnchen / EEF"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eInappropriate Encoding for Output Context vulnerability in joshnuss xml_builder (\u003ccode\u003eXmlBuilder\u003c/code\u003e module) allows Content Spoofing, Cross-site Scripting.\u003c/p\u003e\n\u003cp\u003eThis vulnerability is associated with program files \u003ccode\u003elib/xml_builder.ex\u003c/code\u003e and program routines \u003ccode\u003eXmlBuilder.generate/1\u003c/code\u003e, \u003ccode\u003eXmlBuilder.generate/2\u003c/code\u003e, \u003ccode\u003eXmlBuilder.escape_string/1\u003c/code\u003e, \u003ccode\u003eXmlBuilder.escape_entity/1\u003c/code\u003e.\u003c/p\u003e\n\u003cp\u003e\u003ccode\u003eXmlBuilder.generate/1\u003c/code\u003e does not escape literal \u003ccode\u003e\u0026amp;\u003c/code\u003e characters in text or attribute values when they are followed by an entity-like token (\u003ccode\u003elt;\u003c/code\u003e, \u003ccode\u003egt;\u003c/code\u003e, \u003ccode\u003eamp;\u003c/code\u003e, \u003ccode\u003equot;\u003c/code\u003e, \u003ccode\u003eapos;\u003c/code\u003e). As a result, attacker-supplied input such as \u003ccode\u003e\u0026amp;lt;script\u0026amp;gt;\u003c/code\u003e is emitted verbatim into the serialized XML rather than being escaped to \u003ccode\u003e\u0026amp;amp;lt;script\u0026amp;amp;gt;\u003c/code\u003e. When a downstream XML parser later reads the document, it decodes the entity sequences into the literal characters \u003ccode\u003e\u0026lt;script\u0026gt;\u003c/code\u003e, promoting inert-looking text into real markup. This allows an attacker to bypass upstream filters that block raw \u003ccode\u003e\u0026lt;\u003c/code\u003e and \u003ccode\u003e\u0026gt;\u003c/code\u003e characters, injecting markup into any downstream consumer that parses the produced XML and renders the text content in a markup-sensitive context (HTML, SVG, RSS/Atom feeds). Both element text and attribute values are affected.\u003c/p\u003e\n\u003cp\u003eThis issue affects xml_builder: from 0.0.6 before 2.4.1.\u003c/p\u003e"
},
{
"base64": false,
"type": "text/markdown",
"value": "Inappropriate Encoding for Output Context vulnerability in joshnuss xml_builder (`XmlBuilder` module) allows Content Spoofing, Cross-site Scripting.\n\nThis vulnerability is associated with program files `lib/xml_builder.ex` and program routines `XmlBuilder.generate/1`, `XmlBuilder.generate/2`, `XmlBuilder.escape_string/1`, `XmlBuilder.escape_entity/1`.\n\n`XmlBuilder.generate/1` does not escape literal `\u0026` characters in text or attribute values when they are followed by an entity-like token (`lt;`, `gt;`, `amp;`, `quot;`, `apos;`). As a result, attacker-supplied input such as `\u0026lt;script\u0026gt;` is emitted verbatim into the serialized XML rather than being escaped to `\u0026amp;lt;script\u0026amp;gt;`. When a downstream XML parser later reads the document, it decodes the entity sequences into the literal characters `\u003cscript\u003e`, promoting inert-looking text into real markup. This allows an attacker to bypass upstream filters that block raw `\u003c` and `\u003e` characters, injecting markup into any downstream consumer that parses the produced XML and renders the text content in a markup-sensitive context (HTML, SVG, RSS/Atom feeds). Both element text and attribute values are affected.\n\nThis issue affects xml_builder: from 0.0.6 before 2.4.1."
}
],
"value": "Inappropriate Encoding for Output Context vulnerability in joshnuss xml_builder (XmlBuilder module) allows Content Spoofing, Cross-site Scripting.\n\nThis vulnerability is associated with program files lib/xml_builder.ex and program routines XmlBuilder.generate/1, XmlBuilder.generate/2, XmlBuilder.escape_string/1, XmlBuilder.escape_entity/1.\n\nXmlBuilder.generate/1 does not escape literal \u0026 characters in text or attribute values when they are followed by an entity-like token (lt;, gt;, amp;, quot;, apos;). As a result, attacker-supplied input such as \u0026lt;script\u0026gt; is emitted verbatim into the serialized XML rather than being escaped to \u0026amp;lt;script\u0026amp;gt;. When a downstream XML parser later reads the document, it decodes the entity sequences into the literal characters \u003cscript\u003e, promoting inert-looking text into real markup. This allows an attacker to bypass upstream filters that block raw \u003c and \u003e characters, injecting markup into any downstream consumer that parses the produced XML and renders the text content in a markup-sensitive context (HTML, SVG, RSS/Atom feeds). Both element text and attribute values are affected.\n\nThis issue affects xml_builder: from 0.0.6 before 2.4.1."
}
],
"impacts": [
{
"capecId": "CAPEC-120",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-120 Double Encoding"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "LOCAL",
"baseScore": 2.1,
"baseSeverity": "LOW",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "LOW",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-838",
"description": "CWE-838 Inappropriate Encoding for Output Context",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-21T09:52:44.178Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"tags": [
"vendor-advisory",
"related"
],
"url": "https://github.com/joshnuss/xml_builder/security/advisories/GHSA-5hjx-8g53-cmvm"
},
{
"tags": [
"related"
],
"url": "https://cna.erlef.org/cves/CVE-2026-47079.html"
},
{
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-47079"
},
{
"tags": [
"patch"
],
"url": "https://github.com/joshnuss/xml_builder/commit/c3390e2046ec297b3bb8c30d5779cdfd6508c275"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "Round-trip Corruption via Improper Entity Escaping in xml_builder"
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-47079",
"datePublished": "2026-08-21T09:52:44.178Z",
"dateReserved": "2026-05-18T17:28:10.319Z",
"dateUpdated": "2026-08-21T12:19:47.179Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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