high7.5
CVE-2026-27942
fast-xml-parser has stack overflow in XMLBuilder with preserveOrder
Impact
### 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
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | fast-xml-parser | >= 5.0.0, < 5.3.8 | 5.3.8 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Naturalintelligence | Fast-Xml-Parser | before 4.5.4 from 5.0.0 before 5.3.8 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/c13a961910f14986295dd28484eee830fa1a0e8a
- https://github.com/NaturalIntelligence/fast-xml-parser/pull/791
- https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-fj3w-jwp8-x2g3
- https://github.com/advisories/GHSA-fj3w-jwp8-x2g3
- https://nvd.nist.gov/vuln/detail/CVE-2026-27942