CVE-2026-47079

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 &lt;script&gt; is emitted verbatim into the serialized XML rather than being escaped to &amp;lt;script&amp;gt;. 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.

## 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 `&lt;script&gt;` is emitted verbatim into the serialized XML rather than being escaped to `&amp;lt;script&amp;gt;`. 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.

Vulnerabilidad de codificación inapropiada para el contexto de salida en joshnuss xml_builder (módulo XmlBuilder) permite la suplantación de contenido (Content Spoofing), cross-site scripting. Esta vulnerabilidad está asociada con los archivos de programa lib/xml_builder.ex y las rutinas de programa XmlBuilder.generate/1, XmlBuilder.generate/2, XmlBuilder.escape_string/1, XmlBuilder.escape_entity/1. XmlBuilder.generate/1 no escapa los caracteres literales & en texto o valores de atributos cuando van seguidos de un token similar a una entidad (lt;, gt;, amp;, quot;, apos;). Como resultado, la entrada proporcionada por el atacante, como <script>, se emite textualmente en el XML serializado en lugar de ser escapada a <script>. Cuando un analizador XML descendente lee el documento más tarde, decodifica las secuencias de entidades en los caracteres literales <script>, promoviendo texto de apariencia inerte a marcado real. Esto permite a un atacante eludir filtros ascendentes que bloquean los caracteres brutos < y >, inyectando marcado en cualquier consumidor descendente que analiza el XML producido y renderiza el contenido de texto en un contexto sensible al marcado (HTML, SVG, RSS/Atom feeds). Tanto el texto de los elementos como los valores de los atributos se ven afectados. Este problema afecta a xml_builder: desde 0.0.6 antes de 2.4.1.