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7.5
HIGH CVSS 3.1
CVE-2026-27942
fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
Overview
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.

Details
INFO

Published Date :

Feb. 26, 2026, 2:16 a.m.

Last Modified :

March 2, 2026, 2:54 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
Impact
Affected Products

The following products are affected by CVE-2026-27942 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Fast-xml-parser_project fast-xml-parser
1 Naturalintelligence fast-xml-parser
: Total Affected Vendor : 2 | Products : 2
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 HIGH [email protected]
CVSS 4.0 LOW [email protected]
Solution
Update fast-xml-parser to version 5.3.8 or newer to prevent stack overflow crashes.
  • Update fast-xml-parser to version 5.3.8 or later.
  • Use XML builder with `preserveOrder:false`.
  • Validate input data before building XML.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-27942.

URL Resource
https://github.com/NaturalIntelligence/fast-xml-parser/commit/c13a961910f14986295dd28484eee830fa1a0e8a Patch
https://github.com/NaturalIntelligence/fast-xml-parser/pull/791 Issue Tracking Patch
https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-fj3w-jwp8-x2g3 Vendor Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-27942 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-27942 weaknesses.

CAPEC-8: Buffer Overflow in an API Call Buffer Overflow in an API Call CAPEC-9: Buffer Overflow in Local Command-Line Utilities Buffer Overflow in Local Command-Line Utilities CAPEC-10: Buffer Overflow via Environment Variables Buffer Overflow via Environment Variables CAPEC-14: Client-side Injection-induced Buffer Overflow Client-side Injection-induced Buffer Overflow CAPEC-24: Filter Failure through Buffer Overflow Filter Failure through Buffer Overflow CAPEC-42: MIME Conversion MIME Conversion CAPEC-44: Overflow Binary Resource File Overflow Binary Resource File CAPEC-45: Buffer Overflow via Symbolic Links Buffer Overflow via Symbolic Links CAPEC-46: Overflow Variables and Tags Overflow Variables and Tags CAPEC-47: Buffer Overflow via Parameter Expansion Buffer Overflow via Parameter Expansion CAPEC-67: String Format Overflow in syslog() String Format Overflow in syslog() CAPEC-92: Forced Integer Overflow Forced Integer Overflow CAPEC-100: Overflow Buffers Overflow Buffers

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-27942 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-27942 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Reanalysis by [email protected]

    Mar. 02, 2026

    Action Type Old Value New Value
    Changed CPE Configuration OR *cpe:2.3:a:fast-xml-parser_project:fast-xml-parser:*:*:*:*:*:node.js:*:* versions up to (excluding) 4.5.4 *cpe:2.3:a:fast-xml-parser_project:fast-xml-parser:*:*:*:*:*:node.js:*:* versions from (including) 5.0.0 up to (excluding) 5.3.8 OR *cpe:2.3:a:naturalintelligence:fast-xml-parser:*:*:*:*:*:*:*:* versions up to (excluding) 4.5.4 *cpe:2.3:a:naturalintelligence:fast-xml-parser:*:*:*:*:*:*:*:* versions from (including) 5.0.0 up to (excluding) 5.3.8
  • Initial Analysis by [email protected]

    Feb. 27, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
    Added CPE Configuration OR *cpe:2.3:a:fast-xml-parser_project:fast-xml-parser:*:*:*:*:*:node.js:*:* versions up to (excluding) 4.5.4 *cpe:2.3:a:fast-xml-parser_project:fast-xml-parser:*:*:*:*:*:node.js:*:* versions from (including) 5.0.0 up to (excluding) 5.3.8
    Added Reference Type GitHub, Inc.: https://github.com/NaturalIntelligence/fast-xml-parser/commit/c13a961910f14986295dd28484eee830fa1a0e8a Types: Patch
    Added Reference Type GitHub, Inc.: https://github.com/NaturalIntelligence/fast-xml-parser/pull/791 Types: Issue Tracking, Patch
    Added Reference Type GitHub, Inc.: https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-fj3w-jwp8-x2g3 Types: Vendor Advisory
  • New CVE Received by [email protected]

    Feb. 26, 2026

    Action Type Old Value New Value
    Added 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.
    Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
    Added CWE CWE-120
    Added Reference https://github.com/NaturalIntelligence/fast-xml-parser/commit/c13a961910f14986295dd28484eee830fa1a0e8a
    Added Reference https://github.com/NaturalIntelligence/fast-xml-parser/pull/791
    Added Reference https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-fj3w-jwp8-x2g3
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
Base CVSS Score: 2.7
Attack Vector
Attack Complexity
Attack Requirements
Privileges Required
User Interaction
VS Confidentiality
VS Integrity
VS Availability
SS Confidentiality
SS Integrity
SS Availability
Base CVSS Score: 7.5
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact