cvedb.io
CVE-2026-33349
MEDIUM · CVSS 5.9
EPSS exploitation probability: 0%
Published 2026-03-24T20:16:29.407 · Last modified 2026-06-17T10:37:21.500

Summary

fast-xml-parser allows users to process XML from JS object without C/C++ based libraries or callbacks. From version 4.0.0-beta.3 to before version 5.5.7, the DocTypeReader in fast-xml-parser uses JavaScript truthy checks to evaluate maxEntityCount and maxEntitySize configuration limits. When a developer explicitly sets either limit to 0 — intending to disallow all entities or restrict entity size to zero bytes — the falsy nature of 0 in JavaScript causes the guard conditions to short-circuit, completely bypassing the limits. An attacker who can supply XML input to such an application can trigger unbounded entity expansion, leading to memory exhaustion and denial of service. This issue has been patched in version 5.5.7.

Affected products

naturalintelligence — fast-xml-parser

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.