All vulnerabilities

CVE-2026-27942

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

Description

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?

Patch Available

Fix available through Seal Security. No upgrade required, protect your application instantly.

Fix without upgrading
Score
2.7
Severity
Low
Ecosystem
JavaScript
Publish Date
February 26, 2026
Modified Date
March 6, 2026
Score 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
Affected Versions