GHSA-5WM8-GMM8-39J9
Vulnerability from github – Published: 2026-05-08 16:29 – Updated: 2026-05-08 16:29
VLAI?
Summary
fast-xml-builder allows attribute values with unwanted quotes to bypass malicious or unwanted attributes
Details
Summary
When an input data has quotes in attribute values but process entities is not enabled, it breaks the attribute value into multiple attributes. This gives the room for an attacker to insert unwanted attributes to the XML/HTML.
Detail
Malicious Input
{
a: {
"@_attr": '" onClick="alert(1)'
}
}
Output
<a attr="" onClick="alert(1)"></a>
Workarounds
If you're not ignoring attributes then keep processEntities flag true.
Severity ?
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.1.6"
},
"package": {
"ecosystem": "npm",
"name": "fast-xml-builder"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.1.7"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-44665"
],
"database_specific": {
"cwe_ids": [
"CWE-611"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-08T16:29:10Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "# Summary\nWhen an input data has quotes in attribute values but process entities is not enabled, it breaks the attribute value into multiple attributes. This gives the room for an attacker to insert unwanted attributes to the XML/HTML.\n\n## Detail\n\nMalicious Input\n```\n{\n a: {\n \"@_attr\": \u0027\" onClick=\"alert(1)\u0027\n }\n}\n```\n\nOutput\n```xml\n\u003ca attr=\"\" onClick=\"alert(1)\"\u003e\u003c/a\u003e\n```\n\n### Workarounds\nIf you\u0027re not ignoring attributes then keep processEntities flag true.",
"id": "GHSA-5wm8-gmm8-39j9",
"modified": "2026-05-08T16:29:10Z",
"published": "2026-05-08T16:29:10Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/NaturalIntelligence/fast-xml-builder/security/advisories/GHSA-5wm8-gmm8-39j9"
},
{
"type": "PACKAGE",
"url": "https://github.com/NaturalIntelligence/fast-xml-builder"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "fast-xml-builder allows attribute values with unwanted quotes to bypass malicious or unwanted attributes"
}
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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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