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Vulnerability · Published Feb 26, 2026 · Assigned by GitHub_M

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

Low 2.7

In plain English

A low-severity buffer overflow in fast-xml-parser from NaturalIntelligence. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 46% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)2.7Low
Exploit odds (30 days)0.5%top 54.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12node-webfontno fix listedDEBIAN-CVE-2026-27942
Debian:13node-webfontno fix listedDEBIAN-CVE-2026-27942
Debian:14node-webfontno fix listedDEBIAN-CVE-2026-27942
Ubuntu:24.04:LTSnode-webfontno fix listedUBUNTU-CVE-2026-27942
Ubuntu:25.10node-webfontno fix listedUBUNTU-CVE-2026-27942
Ubuntu:26.04:LTSnode-webfontno fix listedUBUNTU-CVE-2026-27942
Ubuntu:26.10node-webfontno fix listedUBUNTU-CVE-2026-27942
npmfast-xml-parser4.5.4GHSA-fj3w-jwp8-x2g3
npmfast-xml-parser5.3.8GHSA-fj3w-jwp8-x2g3

Affected products (as reported)

VendorProductVersions
NaturalIntelligence fast-xml-parser < 5.3.8

Weakness: CWE-120 · Vector: 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

References