EEF-CVE-2026-47079
Round-trip Corruption via Improper Entity Escaping in xml_builder
Quick fix
EEF-CVE-2026-47079 — xml_builder: upgrade to the fixed version with the command below.
mix deps.update xml_builderDetails
## 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 &lt;script&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.
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