CVE-2026-27942

Severity CVSS v4.0:

LOW

Type:

CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Publication date:

26/02/2026

Last modified:

02/03/2026

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.

Impact

Vector 4.0

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 CVSS v4.0 Severity and Metrics:

Base Score: 2.70 LOW
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

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): None
Privileges Required (PR): None
User Interaction (UI): None
Confidentiality (VC): None
Integrity (VI): None
Availability (VA): Low
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None
Exploit Maturity (E): Unreported

Base Score 4.0

2.70

Severity 4.0

LOW

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.50 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x

7.50

Severity 3.x

HIGH

Vulnerable products and versions

CPE	From	Up to
cpe:2.3:a:naturalintelligence:fast-xml-parser::::::::		4.5.4 (excluding)
cpe:2.3:a:naturalintelligence:fast-xml-parser::::::::	5.0.0 (including)	5.3.8 (excluding)

To consult the complete list of CPE names with products and versions, see this page

CVE-2026-27942

Description

Impact

Vulnerable products and versions

References to Advisories, Solutions, and Tools