CVE-2026-27942
published 2026-02-26CVE-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…
PriorityP342high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
0.48%
38.6th percentile
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.
Affected
7 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | node-webfont | — | — |
| naturalintelligence | fast-xml-parser | < 5.3.8 | 5.3.8 |
| naturalintelligence | fast-xml-parser | < 4.5.4 | 4.5.4 |
| naturalintelligence | fast-xml-parser | >= 0 < 5.7.0 | 5.7.0 |
| naturalintelligence | fast-xml-parser | >= 4.0.0-beta.0 < 4.5.4 | 4.5.4 |
| naturalintelligence | fast-xml-parser | >= 5.0.0 < 5.3.8 | 5.3.8 |
| naturalintelligence | fast-xml-parser | >= 5.0.0 < 5.3.8 | 5.3.8 |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvdv4.02.7LOWCVSS: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
ghsa6.5MEDIUM
osv2.7LOW
vendor_debian2.7LOW
vendor_redhat2.7LOW
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GHSA
fast-xml-parser XMLBuilder: XML Comment and CDATA Injection via Unescaped Delimiters
ghsa·2026-04-22·CVSS 6.5
CVE-2026-41650 [MEDIUM] CWE-91 fast-xml-parser XMLBuilder: XML Comment and CDATA Injection via Unescaped Delimiters
fast-xml-parser XMLBuilder: XML Comment and CDATA Injection via Unescaped Delimiters
# fast-xml-parser XMLBuilder: Comment and CDATA Injection via Unescaped Delimiters
## Summary
fast-xml-parser XMLBuilder does not escape the `-->` sequence in comment content or the `]]>` sequence in CDATA sections when building XML from JavaScript objects. This allows XML injection when user-controlled data flows into comments or CDATA elements, leading to XSS, SOAP injection, or data manipulation.
Existing CVEs for fast-xml-parser cover different issues:
- CVE-2023-26920: Prototype pollution (parser)
- CVE-2023-34104: ReDoS (parser)
- CVE-2026-27942: Stack overflow in XMLBuilder with preserveOrder
- CVE-2026-25896: Entity encoding bypass via regex in DOCTYPE entities
This finding covers **unescaped
OSV
fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
osv·2026-02-26
CVE-2026-27942 [LOW] fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
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?_](https://github.com/NaturalIntelligence/fast-xml-parser/pull/791)
OSV
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
osv·2026-02-26·CVSS 2.7
CVE-2026-27942 [LOW] 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
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.
GHSA
fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
ghsa·2026-02-26
CVE-2026-27942 [LOW] CWE-120 fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
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?_](https://github.com/NaturalIntelligence/fast-xml-parser/pull/791)
Red Hat
fast-xml-parser: fast-xml-parser: Stack overflow leads to Denial of Service
vendor_redhat·2026-02-26·CVSS 2.7
CVE-2026-27942 [LOW] CWE-776 fast-xml-parser: fast-xml-parser: Stack overflow leads to Denial of Service
fast-xml-parser: fast-xml-parser: Stack overflow leads to Denial of Service
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.
A flaw was found in fast-xml-parser. A user can exploit this flaw by processing specially crafted XML data with the XML builder when the `preserveOrder` option is enabled. This can lead to a stack overflow, causing the application to crash and resulting in a Denial of Service (DoS).
Statement: The flaw affects t
Debian
CVE-2026-27942: node-webfont - fast-xml-parser allows users to validate XML, parse XML to JS object, or build X...
vendor_debian·2026·CVSS 2.7
CVE-2026-27942 [LOW] CVE-2026-27942: node-webfont - fast-xml-parser allows users to validate XML, parse XML to JS object, or build X...
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.
Scope: local
bookworm: undetermined
forky: undetermined
sid: undetermined
trixie: undetermined
No detection rules found.
No public exploits indexed.
Wiz
CVE-2026-27942 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 2.7
CVE-2026-27942 [LOW] CVE-2026-27942 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-27942 :
JavaScript vulnerability analysis and mitigation
preserveOrder:true
preserveOrder:false
Source : NVD
## 2.7
Score
Published February 26, 2026
Severity LOW
CNA Score 2.7
Affected Technologies
JavaScript
Wolfi
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 16.9
Exploitation Probability (EPSS) 0.1
Affected packages and libraries
kibana-8.19
kibana-9.2
Sources
NVD
Chainguard Has Fix Added at: Mar 02, 2026
Echo Severity HIGH No Fix Added at: Mar 02, 2026
npm Severity LOW Has Fix Added at: Mar 02, 2026
MinimOS Severity HIGH Has Fix Added at: Mar 09, 2026
Wolfi Has Fix Added at: Mar 02, 2026
## Get a CVE risk assessment
Get a prioritized view of CVEs in y
Bugzilla
CVE-2026-27942 h3: fast-xml-parser: Stack overflow leads to Denial of Service [fedora-42]
bugzilla·2026-02-26·CVSS 2.7
CVE-2026-27942 [LOW] CVE-2026-27942 h3: fast-xml-parser: Stack overflow leads to Denial of Service [fedora-42]
CVE-2026-27942 h3: fast-xml-parser: Stack overflow leads to Denial of Service [fedora-42]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Discussion:
This message is a reminder that Fedora Linux 42 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora Linux 42 on 2026-05-13.
It is Fedora's policy to close all bug reports from releases that are no longer
maintained. At that time this bug will be closed as EOL if it remains open with a
'version' of '42'.
Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, change
Bugzilla
CVE-2026-27942 fast-xml-parser: fast-xml-parser: Stack overflow leads to Denial of Service
bugzilla·2026-02-26·CVSS 2.7
CVE-2026-27942 [LOW] CVE-2026-27942 fast-xml-parser: fast-xml-parser: Stack overflow leads to Denial of Service
CVE-2026-27942 fast-xml-parser: fast-xml-parser: Stack overflow leads to Denial of Service
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.
2026-02-26
Published