High 7.5Published Mar 20, 2026

CVE-2026-33036fast-xml-parser allows users to process XML from JS object without C/C++ based libraries or callbacks.

Updated under an hour ago (2026-10-19 08:00 UTC)

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It affects naturalintelligence fast-xml-parser. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for naturalintelligence fast-xml-parser

Exploited in the last 30 days

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 entities completely evade the entity expansion limits (e.g., maxTotalExpansions, maxExpandedLength) added to fix CVE-2026-26278, enabling XML entity expansion Denial of Service. The root cause is that replaceEntitiesValue() in OrderedObjParser.js only enforces expansion counting on DOCTYPE-defined entities while the lastEntities loop handling numeric/standard entities performs no counting at all. An attacker supplying 1M numeric entity references like A can force ~147MB of memory allocation and heavy CPU usage, potentially crashing the process—even when developers have configured strict limits. This issue has been fixed in version 5.5.6.

CVSS: 7.5 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-776
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Analyzed
Record last updated: Jun 17, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

naturalintelligence fast-xml-parser naturalintelligence:fast-xml-parser	from 4.0.1 before 5.5.6; 4.0.0; 4.0.0; 4.0.0; 4.0.0; 4.0.0; 4.0.0; 4.0.0	NVD

References

https://github.com/NaturalIntelligence/fast-xml-parser/commit/bd26122c838e6a55e7d7ac49b4ccc01a49999a01patch
https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.5.6product, release-notes
https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-8gc5-j5rx-235rexploit, mitigation, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.