CVE-2026-27942
High
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. Prior to version 5.3.8, the application crashes with stack overflow when user use XML builder with `preserveOrder:true`. Version 5.3.8 fixes the issue. As a workaround, use XML builder with `preserveOrder:false` or check the input data before passing to builder.
SeverityHigh
CVSS7.5
Exploit probability—
ProductNaturalintelligence Fast-xml-parser
PublishedFeb 26, 2026
First seenFeb 26, 2026
Weakness typeCWE-120CWE-120
How to fix
Update
- naturalintelligence fast-xml-parser4.5.4, 5.3.8 or later
- fast-xml-parser5.3.8, 4.5.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| naturalintelligence fast-xml-parser | v < 4.5.4, 5.0.0 ≤ v < 5.3.8 | 4.5.4, 5.3.8 |
| fast-xml-parsernpm | 5.0.0 ≤ v < 5.3.8, 4.0.0-beta.0 ≤ v < 4.5.4 | 5.3.8, 4.5.4 |
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