XXE in Naturalintelligence Fast-xml-parser
CVE-2026-33036
fast-xml-parser allows users to process XML from JS object without C/C++ based libraries or callbacks. Versions 4.0.0-beta.3 through 5.5.5 contain a bypass vulnerability where numeric character references (&#NNN;, &#xHH;) and standard XML…
EPSS: 0.000 (8.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Naturalintelligence Fast-xml-parser — versions >= 4.0.0-beta.3, < 5.5.6
Weakness classification (CWE)
References
- https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-8gc5-j5rx-235r (x_refsource_CONFIRM)
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/bd26122c838e6a55e7d7ac49b4ccc01a49999a01 (x_refsource_MISC)
- https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.5.6 (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-33036?
- CVE-2026-33036 is a high-severity vulnerability in Naturalintelligence Fast-xml-parser, classified under Improper Restriction of Recursive Entity References in DTDs (XML Entity Expansion). CVSS score: 7.5/10. Published 2026-03-20.
- How severe is CVE-2026-33036?
- High severity. CVSS v3 base score is 7.5 out of 10.