CVE-2026-27942
fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
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.
- Record
CVE-2026-27942- CVSS 4.0
- 2.7 Low
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 - Weakness
- CWE-120
- Updated
- 2026-11-02
EUVDEUVD-2026-8811
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.
- Record
EUVD-2026-8811- CVSS 4.0
- 2.7 Low
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-fj3w-jwp8-x2g3
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
- Record
GHSA-fj3w-jwp8-x2g3- CVSS 4.0
- 2.7 Low
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 - Weakness
- CWE-120
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-27942- CVSS 4.0
- 2.7 Low
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 - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-120
- Updated
- 2026-11-02
OSV
fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
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.
- Record
CVE-2026-27942- CVSS 4.0
- 2.7 Low
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 - Weakness
- CWE-120
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-27942
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.
- Record
DEBIAN-CVE-2026-27942- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Show 9 moreShow less
OSVGHSA-fj3w-jwp8-x2g3
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
- Record
GHSA-fj3w-jwp8-x2g3- CVSS 4.0
- 2.7 Low
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 - Weakness
- CWE-120
- Updated
- 2026-11-02
OSVROOT-APP-NPM-CVE-2026-27942
CVE-2026-27942 in @rootio/fast-xml-parser - Patched by Root
Root has patched CVE-2026-27942 in the @rootio/fast-xml-parser package for Root:npm. Multiple fixed versions available.
- Record
ROOT-APP-NPM-CVE-2026-27942- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-27942
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.
- Record
UBUNTU-CVE-2026-27942- CVSS 4.0
- 2.7 Low
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 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVCLSA-2026-1776818199 No score
TuxCare security update for fast-xml-parser (2 CVEs)
TuxCare rebuilt fast-xml-parser to address 2 CVEs. Fixed in 4.5.3-tuxcare.2.
- Record
CLSA-2026-1776818199- Updated
- 2026-11-02
OSVCLSA-2026-1781744119 No score
TuxCare security update for fast-xml-parser (6 CVEs)
TuxCare rebuilt fast-xml-parser to address 6 CVEs. Fixed in 4.2.7-tuxcare.1.
- Record
CLSA-2026-1781744119- Updated
- 2026-11-02
OSVCLSA-2026-1781744139 No score
TuxCare security update for fast-xml-parser (6 CVEs)
TuxCare rebuilt fast-xml-parser to address 6 CVEs. Fixed in 4.4.0-tuxcare.1.
- Record
CLSA-2026-1781744139- Updated
- 2026-11-05
OSVCLSA-2026-1789289706 No score
TuxCare security update for fast-xml-parser (1 CVE)
TuxCare rebuilt fast-xml-parser to address 1 CVE. Fixed in 4.5.1-tuxcare.1.
- Record
CLSA-2026-1789289706- Updated
- 2026-11-02
OSVCLSA-2026-1792454133 No score
TuxCare security update for fast-xml-parser (7 CVEs)
TuxCare rebuilt fast-xml-parser to address 7 CVEs. Fixed in 5.2.5-tuxcare.1.
- Record
CLSA-2026-1792454133- Updated
- 2026-11-02
OSVCLSA-2026-1792488947 No score
TuxCare security update for fast-xml-parser (3 CVEs)
TuxCare rebuilt fast-xml-parser to address 3 CVEs. Fixed in 4.4.1-tuxcare.1.
- Record
CLSA-2026-1792488947- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
fast-xml-parsernpm |
5.0.0 up to 5.3.8 | 5.3.8 |
fast-xml-parsernpm |
4.0.0-beta.0 up to 4.5.4 | 4.5.4 |
fast-xml-parserTuxCare:npm From an advisory covering 2 CVEs |
4.5.3-tuxcare.0 up to 4.5.3-tuxcare.2, plus listed versions 4.5.34.5.3-tuxcare.1 |
4.5.3-tuxcare.2 |
fast-xml-parserTuxCare:npm From an advisory covering 6 CVEs |
4.2.7-tuxcare.0 up to 4.2.7-tuxcare.1, plus listed versions 4.2.7 |
4.2.7-tuxcare.1 |
fast-xml-parserTuxCare:npm From an advisory covering 6 CVEs |
4.4.0-tuxcare.0 up to 4.4.0-tuxcare.1, plus listed versions 4.4.0 |
4.4.0-tuxcare.1 |
fast-xml-parserTuxCare:npm |
4.5.1-tuxcare.0 up to 4.5.1-tuxcare.1, plus listed versions 4.5.1 |
4.5.1-tuxcare.1 |
fast-xml-parserTuxCare:npm From an advisory covering 7 CVEs |
5.2.5-tuxcare.0 up to 5.2.5-tuxcare.1, plus listed versions 5.2.5 |
5.2.5-tuxcare.1 |
fast-xml-parserTuxCare:npm From an advisory covering 3 CVEs |
4.4.1-tuxcare.0 up to 4.4.1-tuxcare.1, plus listed versions 4.4.1 |
4.4.1-tuxcare.1 |
node-webfontDebian:12 |
All versions, plus listed versions 11.4.0+dfsg2+~cs35.7.26-1011.4.0+dfsg2+~cs35.7.26-1111.4.0+dfsg2+~cs35.7.26-1211.4.0+dfsg2+~cs35.7.26-1311.4.0+dfsg2+~cs35.7.26-14 Show 9 moreShow less11.4.0+dfsg2+~cs35.7.26-1511.4.0+dfsg2+~cs35.7.26-1611.4.0+dfsg2+~cs35.7.26-1811.4.0+dfsg2+~cs35.7.26-1911.4.0+dfsg2+~cs35.7.26-2011.4.0+dfsg2+~cs35.7.26-2111.4.0+dfsg2+~cs35.7.26-711.4.0+dfsg2+~cs35.7.26-811.4.0+dfsg2+~cs35.7.26-9 |
None known |
node-webfontDebian:13 |
All versions, plus listed versions 11.4.0+dfsg2+~cs35.7.26-1311.4.0+dfsg2+~cs35.7.26-1411.4.0+dfsg2+~cs35.7.26-1511.4.0+dfsg2+~cs35.7.26-1611.4.0+dfsg2+~cs35.7.26-1811.4.0+dfsg2+~cs35.7.26-1911.4.0+dfsg2+~cs35.7.26-2011.4.0+dfsg2+~cs35.7.26-21 |
None known |
Show 7 moreShow less
| Package | Affected | Fixed |
|---|---|---|
node-webfontDebian:14 |
All versions, plus listed versions 11.4.0+dfsg2+~cs35.7.26-1311.4.0+dfsg2+~cs35.7.26-1411.4.0+dfsg2+~cs35.7.26-1511.4.0+dfsg2+~cs35.7.26-1611.4.0+dfsg2+~cs35.7.26-1811.4.0+dfsg2+~cs35.7.26-1911.4.0+dfsg2+~cs35.7.26-2011.4.0+dfsg2+~cs35.7.26-21 |
None known |
@rootio/fast-xml-parserRoot:npm |
before 5.3.4-root.io.3 | 5.3.4-root.io.34.4.1-root.io.45.3.4-root.io.45.3.6-root.io.24.4.1-root.io.54.4.1-root.io.64.4.1-root.io.75.3.4-root.io.55.3.6-root.io.35.2.5-root.io.24.4.1-root.io.85.2.5-root.io.35.3.4-root.io.65.3.6-root.io.44.4.1-root.io.95.2.5-root.io.45.3.4-root.io.75.3.6-root.io.55.3.4-root.io.85.3.6-root.io.64.5.4-root.io.1 |
fast-xml-parserRoot:npm |
before 4.4.1-aikido.9 | 4.4.1-aikido.95.2.5-aikido.45.3.4-aikido.75.3.6-aikido.55.3.4-aikido.85.3.6-aikido.64.5.4-aikido.1 |
node-webfontUbuntu:24.04:LTS |
All versions, plus listed versions 11.4.0+dfsg2+~cs35.7.26-7ubuntu1 |
None known |
node-webfontUbuntu:25.10 |
All versions, plus listed versions 11.4.0+dfsg2+~cs35.7.26-1011.4.0+dfsg2+~cs35.7.26-13ubuntu2 |
None known |
node-webfontUbuntu:26.10 |
All versions, plus listed versions 11.4.0+dfsg2+~cs35.7.26-1811.4.0+dfsg2+~cs35.7.26-19 |
None known |
node-webfontUbuntu:26.04:LTS |
All versions, plus listed versions 11.4.0+dfsg2+~cs35.7.26-13ubuntu211.4.0+dfsg2+~cs35.7.26-1411.4.0+dfsg2+~cs35.7.26-1511.4.0+dfsg2+~cs35.7.26-16build111.4.0+dfsg2+~cs35.7.26-18 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected | ||
| facts | OSV | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-27942 is a low vulnerability (CVSS 2.7) in Naturalintelligence Fast-xml-parser, published February 26, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.54%, the 45th percentile. Fixed in fast-xml-parser 5.3.8.
References
github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-fj3w-jwp8-x2g3
nvd.nist.gov/vuln/detail/CVE-2026-27942