CVE-2026-27942
HIGH7.5EPSS 0.02%fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
Published: 2/26/2026Modified: 3/6/2026
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?_](https://github.com/NaturalIntelligence/fast-xml-parser/pull/791)
Affected packages (2)
- Debian/node-webfontfrom 0
- npm/fast-xml-parser>= 5.0.0, < 5.3.8
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 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 |
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
References (6)
- ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-27942
- ADVISORYhttps://security-tracker.debian.org/tracker/CVE-2026-27942
- PATCHhttps://github.com/NaturalIntelligence/fast-xml-parser
- WEBhttps://github.com/NaturalIntelligence/fast-xml-parser/commit/c13a961910f14986295dd28484eee830fa1a0e8a
- WEBhttps://github.com/NaturalIntelligence/fast-xml-parser/pull/791
- WEBhttps://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-fj3w-jwp8-x2g3