Low 2.7Published Feb 25, 2026

CVE-2026-27942fast-xml-parser has stack overflow in XMLBuilder with preserveOrder

Updated under an hour ago (Oct 28, 2026, 1:50 AM ET)

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It affects NaturalIntelligence fast-xml-parser and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for NaturalIntelligence fast-xml-parser

Exploited in the last 30 days

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.

CVSS: 2.7 LOW (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Weakness (CWE): CWE-120
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jun 23, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

NaturalIntelligence fast-xml-parser naturalintelligence:fast_xml_parser (from the name)	before 5.3.8	CNA record
naturalintelligence fast-xml-parser naturalintelligence:fast-xml-parser	before 4.5.4; from 5.0.0 before 5.3.8	NVD

References

References

https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-fj3w-jwp8-x2g3	x-refsource-confirm, vendor-advisory
https://github.com/NaturalIntelligence/fast-xml-parser/pull/791	x-refsource-misc, issue-tracking, patch
https://github.com/NaturalIntelligence/fast-xml-parser/commit/c13a961910f14986295dd28484eee830fa1a0e8a	x-refsource-misc, patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.