Get a Demo

Let's Patch It!

Book a short call with one our specialists, we'll walk you through how Endor Patches work, and ask you a few questions about your environment (like your primary programming languages and repository management). We'll also send you an email right after you fill out the form, feel free to reply with any questions you have in advance!

CVE

CVE-2026-27942

fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
Back to all
CVE

CVE-2026-27942

fast-xml-parser has stack overflow in XMLBuilder with preserveOrder

Impact

Application crashes with stack overflow when user use XML builder with prserveOrder:true for following or similar input 

[{
    'foo': [
        { 'bar': [{ '@_V': 'baz' }] }
    ]
}]

Cause: arrToStr was not validating if the input is an array or a string and treating all non-array values as text content.

What kind of vulnerability is it? Who is impacted?

Patches

Yes in 5.3.8

Workarounds

Use XML builder with preserveOrder:false or check the input data before passing to builder.

References

Are there any links users can visit to find out more?

Package Versions Affected

Package Version
patch Availability
No items found.

Automatically patch vulnerabilities without upgrading

Fix Without Upgrading
Detect compatible fix
Apply safe remediation
Fix with a single pull request

CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
2.7
-
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/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
C
H
U
0
-
C
H
U
-

Related Resources

No items found.

References

https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-fj3w-jwp8-x2g3, https://nvd.nist.gov/vuln/detail/CVE-2026-27942, https://github.com/NaturalIntelligence/fast-xml-parser/pull/791, https://github.com/NaturalIntelligence/fast-xml-parser/commit/c13a961910f14986295dd28484eee830fa1a0e8a, https://github.com/NaturalIntelligence/fast-xml-parser

Severity

7.5

CVSS Score
0
10

Basic Information

Ecosystem
Base CVSS
7.5
EPSS Probability
0.00056%
EPSS Percentile
0.17531%
Introduced Version
5.0.0,4.0.0-beta.0,0
Fix Available
5.3.8,4.5.4,8.17.10-r11,9.0.8-r11,9.1.10-r6,9.2.6-r2,9.3.1-r1,2.95.12-r12,0.8.2-r6,3.5.0-r2,5.14.3-r8,43.48.3-r0,5.5.0-r6,5.5.0-r7

Fix Critical Vulnerabilities Instantly

Secure your app without upgrading.
Fix Without Upgrading