{"id":"EEF-CVE-2026-47079","summary":"Round-trip Corruption via Improper Entity Escaping in xml_builder","details":"## Summary\n\nInappropriate 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 `&` 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 `\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.","aliases":["CVE-2026-47079","GHSA-5hjx-8g53-cmvm"],"modified":"2026-09-08T05:30:35.451439306Z","published":"2026-08-21T09:52:44.178Z","database_specific":{"capec_ids":["CAPEC-120"],"cpe_ids":["cpe:2.3:a:joshnuss:xml_builder:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-838"]},"references":[{"type":"ADVISORY","url":"https://github.com/joshnuss/xml_builder/security/advisories/GHSA-5hjx-8g53-cmvm"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-47079.html"},{"type":"FIX","url":"https://github.com/joshnuss/xml_builder/commit/c3390e2046ec297b3bb8c30d5779cdfd6508c275"},{"type":"PACKAGE","url":"https://hex.pm/packages/xml_builder"}],"affected":[{"package":{"name":"xml_builder","ecosystem":"Hex","purl":"pkg:hex/xml_builder"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.0.6"},{"fixed":"2.4.1"}]}],"versions":["0.0.6","0.0.7","0.0.8","0.0.9","0.1.0","0.1.1","0.1.2","2.0.0","2.1.0","2.1.1","2.1.2","2.1.4","2.2.0","2.3.0","2.4.0"],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-47079.json"}},{"ranges":[{"type":"GIT","repo":"https://github.com/joshnuss/xml_builder","events":[{"introduced":"aae31e6e8ac837bcbb8afb816c0d14324b5cfe2b"},{"fixed":"c3390e2046ec297b3bb8c30d5779cdfd6508c275"}]}],"versions":["v0.0.6"],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-47079.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}],"credits":[{"name":"Peter Ullrich","type":"FINDER"},{"name":"Joshua Nussbaum","type":"REMEDIATION_DEVELOPER"},{"name":"Jonatan Männchen / EEF","type":"COORDINATOR"}]}