CVE-2026-25896— fast-xml-parser has an entity encoding bypass via regex injection in DOCTYPE entity names
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I. Basic Information for CVE-2026-25896
Vulnerability Information
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Vulnerability Title
fast-xml-parser has an entity encoding bypass via regex injection in DOCTYPE entity names
Source: NVD (National Vulnerability Database)
Vulnerability Description
fast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based libraries and no callback. From 4.1.3to before 5.3.5, a dot (.) in a DOCTYPE entity name is treated as a regex wildcard during entity replacement, allowing an attacker to shadow built-in XML entities (<, >, &, ", ') with arbitrary values. This bypasses entity encoding and leads to XSS when parsed output is rendered. This vulnerability is fixed in 5.3.5.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N
Source: NVD (National Vulnerability Database)
Vulnerability Type
不正确的正则表达式
Source: NVD (National Vulnerability Database)
Vulnerability Title
fast-xml-parser 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
fast-xml-parser是Natural Intelligence开源的一个库。用于在没有基于 C/C++ 的库和回调的情况下，快速验证 XML、解析 XML 和构建 XML。 fast-xml-parser 4.1.3版本至5.3.5之前版本存在安全漏洞，该漏洞源于DOCTYPE实体名称中的点被当作正则表达式通配符处理，可能导致跨站脚本攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
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Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| NaturalIntelligence | fast-xml-parser | >= 5.0.0, < 5.3.5 | - |
II. Public POCs for CVE-2026-25896
| # | POC Description | Source Link | Shenlong Link |
|---|
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IV. Related Vulnerabilities
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Same vendor: NaturalIntelligence
- CVE-2026-41650
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fast-xml-parser: Entity Expansion Limits Bypassed When Set t - CVE-2026-33036
fast-xml-parser affected by numeric entity expansion bypassi - CVE-2026-27942
fast-xml-parser has stack overflow in XMLBuilder with preser - CVE-2026-26278
fast-xml-parser affected by DoS through entity expansion in
Same weakness: CWE-185
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V. Comments for CVE-2026-25896
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